All questions
Question 1
A teacher wants to compare test score distributions from two different classes. Class 1 has scores mostly between 75-85 with a few scores at 90-95. Class 2 has scores evenly distributed from 60-95. Which characteristic would be most different between these distributions?
- The center values will be most different because Class 1 clusters higher
- The overall shapes will be most different because of clustering patterns
- The spread values will be most different because of the range differences (correct answer)
- The data collection methods will be most different because of score variations
Explanation: The spread will be most different. Class 2 spans 35 points (60-95) evenly, while Class 1 is mostly within 10 points (75-85). Data collection methods are not a distribution characteristic.
Question 2
Six temperature readings (in ∘F) during one day were: 50, 52, 53, 54, 55, 80. Which choice best describes the distribution using center, spread, and shape?
- Center: 55; Spread: 5; Shape: symmetric
- Center: 53.5 (median); Spread: 30 (range); Shape: skewed right with an outlier at 80 (correct answer)
- Center: 80; Spread: 30; Shape: symmetric
- Center: 52; Spread: 20; Shape: skewed left
Explanation: This question tests understanding data distribution characterized by three features: center (typical value like mean/median), spread (variability like range), and overall shape (pattern: symmetric, skewed, clusters, outliers). Distribution characteristics: (1) center describes typical value (where middle is: mean=sum/count, median=middle value when ordered, shows what's typical in data), (2) spread describes variability (how spread out: range=max-min, shows how much values differ), (3) shape describes overall pattern (symmetric: mirror around center, skewed: long tail one direction, clusters: groups separated by gaps, outliers: values far from rest). All three needed for complete description: center alone doesn't tell variability, spread alone doesn't tell typical value, shape shows distribution pattern (together give full picture). For example, test scores 50,52,53,54,55,80, describe: center median=53.5 (typical score, middle of ordered data, resistant to outlier 80), spread range=80-50=30 (scores vary by 30 points, or without outlier: range 5, outlier inflates spread), shape: skewed right with outlier (most scores 50-55 clustered, one high outlier 80 pulls right, not symmetric); or ages 10,12,14,15,16,18,20: center mean=15 median=15 (both at middle), spread range=10 (ages vary 10 years), shape symmetric (values roughly even both sides of 15). The correct description is center at 53.5 (median), spread of 30 (range), and skewed right with an outlier at 80, reflecting the cluster at lower temperatures and the high pull. Incorrect choices might use wrong center like 80 or 55 (not median), incorrect spread like 5 or 20 (miscalculating), or wrong shape like symmetric or skewed left (ignoring right tail). Describing: (1) find center (calculate mean or median: median better with outliers, mean sensitive to extremes), (2) find spread (range=max-min simple for grade 6, or estimate variability visually), (3) describe shape (look at data: symmetric? skewed which way? any outliers far from rest? clusters or gaps?), (4) combine (distribution has center X, spread Y, shape Z—complete picture). Understanding: center tells "where" (typical location), spread tells "how much variability" (tight cluster vs wide spread), shape tells "what pattern" (symmetric bell, skewed with tail, bimodal with two peaks, etc.). Example data: 10,11,12,20,21,22 shows center≈16 (middle), spread≈12 (range 22-10), shape: two clusters (10-12 and 20-22 groups, gap 13-19 between). Mistakes: describing only one or two characteristics (incomplete), wrong calculations (mean or range), shape not described or vague, outliers missed.
Question 3
A researcher collected data on the number of books read by students in two different classes over the summer. Class A has most students reading between 3-5 books with very few reading 0 or 8+ books. Class B has students fairly evenly spread from 0 to 8 books. Which statement best compares the distributions?
- Class A has greater spread and Class B has a more predictable center
- Class B has greater spread and Class A has a more predictable center (correct answer)
- Both classes have similar spread but Class A has a higher center
- Both classes have similar centers but Class B has a lower spread
Explanation: Class B has greater spread because students are evenly distributed across the full range (0-8 books), while Class A is clustered around 3-5 books. Class A has a more predictable center because most values cluster in the middle range. Spread refers to how scattered the data is, and center refers to where the data tends to cluster.
Question 4
Two stores tracked daily customer counts over a month. Store A had consistent daily counts between 45-55 customers. Store B had mostly 20-30 customers per day, but had 80-90 customers on weekend days. When comparing these distributions, what would be the most significant difference in their characteristics?
- Store B shows greater spread values and Store A shows more consistent patterns (correct answer)
- Store A shows greater center values and Store B shows more predictable patterns
- Store A shows symmetric distribution and Store B shows uniform distribution patterns
- Store B shows lower center values and Store A shows more variable timing
Explanation: When analyzing data distributions, you need to compare three key characteristics: center (average), spread (variability), and shape. Think about what each store's customer pattern tells you about these features.
Store A maintains consistent counts of 45-55 customers daily, creating a narrow range with little variability. Store B typically sees 20-30 customers but jumps to 80-90 on weekends, creating much wider variability in the data. For center values, Store A averages around 50 customers daily, while Store B averages lower overall since most days fall in the 20-30 range, with only weekend spikes.
Answer A correctly identifies that Store B shows greater spread (the range from 20 to 90 is much wider than 45 to 55) while Store A shows more consistent patterns (less day-to-day variation). This captures the fundamental difference between these distributions.
Answer B incorrectly claims Store B has more predictable patterns, when actually the weekend spikes make it less predictable than Store A's consistent range. Answer C misidentifies the distribution shapes - Store A isn't necessarily symmetric, and Store B definitely isn't uniform since it has distinct low and high periods. Answer D incorrectly suggests Store A has more variable timing, when Store A is actually the more consistent store.
Remember: spread measures how scattered your data points are, while consistency refers to how predictable the pattern is. High variability means low consistency, and vice versa. Always look for the store or dataset with the wider range of values when identifying greater spread.
Question 5
A survey asked people to rate a movie from 1-10. The results show most ratings clustered around 7-8, with very few ratings below 5 or above 9. Based on this description, what can you predict about the distribution's shape and what it suggests about viewer opinions?
- Left-skewed shape suggesting viewers generally liked it but had some strong disagreement (correct answer)
- Roughly symmetric shape suggesting viewers had mixed and evenly divided opinions about quality
- Right-skewed shape suggesting viewers generally disliked it but some found it acceptable
- Uniform shape suggesting viewers had completely random opinions with no clear preference
Explanation: When analyzing data distributions, you need to visualize how the data points spread out and where they cluster. The key is understanding what "skewed" means and which direction the tail points.
Let's picture this movie rating data: most ratings cluster around 7-8 (the peak), with very few below 5 or above 9. This creates a distribution where the main bulk sits toward the higher end (7-8), but there's a longer tail stretching toward the lower ratings. When the tail extends toward the lower values (left side of a number line), this creates a left-skewed distribution. This pattern suggests most viewers liked the movie (clustering around 7-8), but some viewers strongly disagreed and gave much lower ratings.
Looking at the wrong answers: B describes a symmetric shape, but our data clearly clusters toward one end rather than being evenly distributed around a center. C suggests right-skewed, which would mean the tail points toward higher values - the opposite of what we have. D describes uniform distribution, where all ratings would be equally common, but we're told most cluster around 7-8.
The correct answer is A because left-skewed perfectly describes data that clusters high with a tail extending toward lower values, and this interpretation (generally positive with some strong disagreement) matches the rating pattern.
Study tip: Remember that skewness is named for where the tail points, not where the peak is. Left-skewed = tail points left toward lower values; right-skewed = tail points right toward higher values.
Question 6
A coach measured how many push-ups 6 students did in one minute: 10, 11, 12, 20, 21, 22. Which choice best describes the distribution using center, spread, and shape?
- Center: 16; Spread: range 22−10=12; Shape: roughly symmetric
- Center: 20; Spread: range 22−11=11; Shape: one cluster
- Center: 11; Spread: range 21−10=11; Shape: skewed right
- Center: median 16; Spread: range 22−10=12; Shape: two clusters (10–12 and 20–22) with a gap between 12 and 20 (correct answer)
Explanation: This question tests understanding of data distribution characterized by three features: center (typical value like mean/median), spread (variability like range), and overall shape (pattern: symmetric, skewed, clusters, outliers). Distribution characteristics: (1) center describes typical value (where middle is: mean=sum/count, median=middle value when ordered, shows what's typical in data), (2) spread describes variability (how spread out: range=max-min, shows how much values differ), (3) shape describes overall pattern (symmetric: mirror around center, skewed: long tail one direction, clusters: groups separated by gaps, outliers: values far from rest). All three needed for complete description: center alone doesn't tell variability, spread alone doesn't tell typical value, shape shows distribution pattern (together give full picture). For this data (10,11,12,20,21,22), the correct three-part description is center at median 16, spread with range 22-10=12, and shape with two clusters (10–12 and 20–22) with a gap between 12 and 20. Common errors include wrong center like 11 or 20, incorrect range like 11, or misidentifying shape as symmetric, skewed, or one cluster when there are two clusters with a gap. To describe: (1) find center (calculate mean or median: median better with outliers, mean sensitive to extremes), (2) find spread (range=max-min simple for grade 6, or estimate variability visually), (3) describe shape (look at data: symmetric? skewed which way? any outliers far from rest? clusters or gaps?), (4) combine (distribution has center X, spread Y, shape Z—complete picture). Understanding: center tells 'where' (typical location), spread tells 'how much variability' (tight cluster vs wide spread), shape tells 'what pattern' (symmetric bell, skewed with tail, bimodal with two peaks, etc.); this data shows two clusters with a gap, not skewness.
Question 7
The ages (in years) of 9 kids at a game club are: 10, 10, 11, 11, 11, 12, 12, 12, 15. Which choice best describes the distribution using center, spread, and shape?
- Center: mean 12; Spread: 5; Shape: two clusters with a gap
- Center: 11; Spread: range 15−10=6; Shape: skewed left
- Center: 15; Spread: range 12−10=2; Shape: symmetric
- Center: median 11; Spread: range 15−10=5; Shape: skewed right because 15 is much larger than the others (correct answer)
Explanation: This question tests understanding of data distribution characterized by three features: center (typical value like mean/median), spread (variability like range), and overall shape (pattern: symmetric, skewed, clusters, outliers). Distribution characteristics: (1) center describes typical value (where middle is: mean=sum/count, median=middle value when ordered, shows what's typical in data), (2) spread describes variability (how spread out: range=max-min, shows how much values differ), (3) shape describes overall pattern (symmetric: mirror around center, skewed: long tail one direction, clusters: groups separated by gaps, outliers: values far from rest). All three needed for complete description: center alone doesn't tell variability, spread alone doesn't tell typical value, shape shows distribution pattern (together give full picture). For this data (10,10,11,11,11,12,12,12,15), the correct three-part description is center at median 11, spread with range 15-10=5, and shape skewed right because 15 is much larger than the others. Common errors include wrong center like 15 (maximum), incorrect range like 6 or 2, or misidentifying shape as skewed left, symmetric, or clustered when it's skewed right with an outlier. To describe: (1) find center (calculate mean or median: median better with outliers, mean sensitive to extremes), (2) find spread (range=max-min simple for grade 6, or estimate variability visually), (3) describe shape (look at data: symmetric? skewed which way? any outliers far from rest? clusters or gaps?), (4) combine (distribution has center X, spread Y, shape Z—complete picture). Understanding: center tells 'where' (typical location), spread tells 'how much variability' (tight cluster vs wide spread), shape tells 'what pattern' (symmetric bell, skewed with tail, bimodal with two peaks, etc.); mistakes include describing only one or two characteristics (incomplete), wrong calculations (mean or range), shape not described or vague, outliers missed.
Question 8
A student tracked the number of pages read each day for 8 days: 12, 13, 13, 14, 14, 15, 15, 16. Which choice best describes the distribution using center, spread, and shape?
- Center: 12; Spread: range 16−12=4; Shape: skewed left
- Center: median 14; Spread: range 16−12=4; Shape: roughly symmetric (correct answer)
- Center: 16; Spread: range 15−12=3; Shape: skewed right
- Center: 14; Spread: 4; Shape: two clusters with a gap
Explanation: This question tests understanding of data distribution characterized by three features: center (typical value like mean/median), spread (variability like range), and overall shape (pattern: symmetric, skewed, clusters, outliers). Distribution characteristics: (1) center describes typical value (where middle is: mean=sum/count, median=middle value when ordered, shows what's typical in data), (2) spread describes variability (how spread out: range=max-min, shows how much values differ), (3) shape describes overall pattern (symmetric: mirror around center, skewed: long tail one direction, clusters: groups separated by gaps, outliers: values far from rest). All three needed for complete description: center alone doesn't tell variability, spread alone doesn't tell typical value, shape shows distribution pattern (together give full picture). For this data (12,13,13,14,14,15,15,16), the correct three-part description is center at median 14, spread with range 16-12=4, and shape roughly symmetric. Common errors include wrong center like 16 or 12, incorrect range like 3, or misidentifying shape as skewed right, skewed left, or clustered when it's symmetric. To describe: (1) find center (calculate mean or median: median better with outliers, mean sensitive to extremes), (2) find spread (range=max-min simple for grade 6, or estimate variability visually), (3) describe shape (look at data: symmetric? skewed which way? any outliers far from rest? clusters or gaps?), (4) combine (distribution has center X, spread Y, shape Z—complete picture). Understanding: center tells 'where' (typical location), spread tells 'how much variability' (tight cluster vs wide spread), shape tells 'what pattern' (symmetric bell, skewed with tail, bimodal with two peaks, etc.); this data is tightly symmetric with small spread.
Question 9
A basketball team tracked points scored by one player in 7 games: 12, 14, 14, 15, 16, 16, 18. What is the center (typical value) using the median?
- 18
- 14
- 15 (correct answer)
- 16
Explanation: This question tests understanding of data distribution characterized by three features: center (typical value like mean/median), spread (variability like range), and overall shape (pattern: symmetric, skewed, clusters, outliers). Distribution characteristics: (1) center describes typical value (where middle is: mean=sum/count, median=middle value when ordered, shows what's typical in data), (2) spread describes variability (how spread out: range=max-min, shows how much values differ), (3) shape describes overall pattern (symmetric: mirror around center, skewed: long tail one direction, clusters: groups separated by gaps, outliers: values far from rest); all three needed for complete description: center alone doesn't tell variability, spread alone doesn't tell typical value, shape shows distribution pattern (together give full picture). For example, test scores 50,52,53,54,55,80, describe: center median=53.5 (typical score, middle of ordered data, resistant to outlier 80), spread range=80-50=30 (scores vary by 30 points, or without outlier: range 5, outlier inflates spread), shape: skewed right with outlier (most scores 50-55 clustered, one high outlier 80 pulls right, not symmetric); or ages 10,12,14,15,16,18,20: center mean=15 median=15 (both at middle), spread range=10 (ages vary 10 years), shape symmetric (values roughly even both sides of 15). The correct center is the median=15, which is the middle value in the ordered list for a typical value, especially useful when data are symmetric without outliers. Errors in other choices include miscalculating the median, such as picking 14 (average of some values) or 16 (perhaps confusing with mean) or 18 (the maximum). To describe distributions: (1) find center (calculate mean or median: median better with outliers, mean sensitive to extremes), (2) find spread (range=max-min simple for grade 6, or estimate variability visually), (3) describe shape (look at data: symmetric? skewed which way? any outliers far from rest? clusters or gaps?), (4) combine (distribution has center X, spread Y, shape Z—complete picture). Understanding: center tells 'where' (typical location), spread tells 'how much variability' (tight cluster vs wide spread), shape tells 'what pattern' (symmetric bell, skewed with tail, bimodal with two peaks, etc.); example data: 10,11,12,20,21,22 shows center≈16 (middle), spread≈12 (range 22-10), shape: two clusters (10-12 and 20-22 groups, gap 13-19 between); mistakes: describing only one or two characteristics (incomplete), wrong calculations (mean or range), shape not described or vague, outliers missed.
Question 10
A student says, "The mean of our class's scores is 78, so I have completely described the data." Which response best explains why you need center, spread, AND shape to describe a distribution?
- Because center tells the typical value, spread tells how much the scores vary, and shape shows patterns like skewness, clusters, gaps, or outliers (correct answer)
- Because the mean always tells you whether there are outliers
- Because only spread matters; center and shape are not useful
- Because shape is a single number like the median
Explanation: This question tests understanding data distribution characterized by three features: center (typical value like mean/median), spread (variability like range), and overall shape (pattern: symmetric, skewed, clusters, outliers). Distribution characteristics: (1) center describes typical value (where middle is: mean=sum/count, median=middle value when ordered, shows what's typical in data), (2) spread describes variability (how spread out: range=max-min, shows how much values differ), (3) shape describes overall pattern (symmetric: mirror around center, skewed: long tail one direction, clusters: groups separated by gaps, outliers: values far from rest). All three needed for complete description: center alone doesn't tell variability, spread alone doesn't tell typical value, shape shows distribution pattern (together give full picture). For example, test scores 50,52,53,54,55,80, describe: center median=53.5 (typical score, middle of ordered data, resistant to outlier 80), spread range=80-50=30 (scores vary by 30 points, or without outlier: range 5, outlier inflates spread), shape: skewed right with outlier (most scores 50-55 clustered, one high outlier 80 pulls right, not symmetric); or ages 10,12,14,15,16,18,20: center mean=15 median=15 (both at middle), spread range=10 (ages vary 10 years), shape symmetric (values roughly even both sides of 15). The correct explanation is that center tells the typical value, spread tells how much the scores vary, and shape shows patterns like skewness, clusters, gaps, or outliers, providing a full picture. Incorrect choices might claim only spread matters (ignores others), shape is a number (it's descriptive), or mean always detects outliers (not necessarily). Describing: (1) find center (calculate mean or median: median better with outliers, mean sensitive to extremes), (2) find spread (range=max-min simple for grade 6, or estimate variability visually), (3) describe shape (look at data: symmetric? skewed which way? any outliers far from rest? clusters or gaps?), (4) combine (distribution has center X, spread Y, shape Z—complete picture). Understanding: center tells "where" (typical location), spread tells "how much variability" (tight cluster vs wide spread), shape tells "what pattern" (symmetric bell, skewed with tail, bimodal with two peaks, etc.). Example data: 10,11,12,20,21,22 shows center≈16 (middle), spread≈12 (range 22-10), shape: two clusters (10-12 and 20-22 groups, gap 13-19 between). Mistakes: describing only one or two characteristics (incomplete), wrong calculations (mean or range), shape not described or vague, outliers missed.
Question 11
The number of pages read by 9 students over a weekend was: 5, 6, 6, 7, 7, 7, 8, 8, 15. Which choice best describes the distribution using center, spread, and shape?
- Center: 7 (median); Spread: 10 (range); Shape: skewed right with a high outlier (15) (correct answer)
- Center: 15; Spread: 10; Shape: symmetric
- Center: 7; Spread: 3; Shape: uniform
- Center: 8; Spread: 2; Shape: skewed left
Explanation: This question tests understanding data distribution characterized by three features: center (typical value like mean/median), spread (variability like range), and overall shape (pattern: symmetric, skewed, clusters, outliers). Distribution characteristics: (1) center describes typical value (where middle is: mean=sum/count, median=middle value when ordered, shows what's typical in data), (2) spread describes variability (how spread out: range=max-min, shows how much values differ), (3) shape describes overall pattern (symmetric: mirror around center, skewed: long tail one direction, clusters: groups separated by gaps, outliers: values far from rest). All three needed for complete description: center alone doesn't tell variability, spread alone doesn't tell typical value, shape shows distribution pattern (together give full picture). For example, test scores 50,52,53,54,55,80, describe: center median=53.5 (typical score, middle of ordered data, resistant to outlier 80), spread range=80-50=30 (scores vary by 30 points, or without outlier: range 5, outlier inflates spread), shape: skewed right with outlier (most scores 50-55 clustered, one high outlier 80 pulls right, not symmetric); or ages 10,12,14,15,16,18,20: center mean=15 median=15 (both at middle), spread range=10 (ages vary 10 years), shape symmetric (values roughly even both sides of 15). The correct description is center at 7 (median), spread of 10 (range), and skewed right with a high outlier at 15, capturing the cluster around 5-8 and the tail. Incorrect choices might use wrong center like 15 or 8 (ignoring median), incorrect spread like 3 or 2 (not max-min), or wrong shape like symmetric or uniform (ignoring skew and outlier). Describing: (1) find center (calculate mean or median: median better with outliers, mean sensitive to extremes), (2) find spread (range=max-min simple for grade 6, or estimate variability visually), (3) describe shape (look at data: symmetric? skewed which way? any outliers far from rest? clusters or gaps?), (4) combine (distribution has center X, spread Y, shape Z—complete picture). Understanding: center tells "where" (typical location), spread tells "how much variability" (tight cluster vs wide spread), shape tells "what pattern" (symmetric bell, skewed with tail, bimodal with two peaks, etc.). Example data: 10,11,12,20,21,22 shows center≈16 (middle), spread≈12 (range 22-10), shape: two clusters (10-12 and 20-22 groups, gap 13-19 between). Mistakes: describing only one or two characteristics (incomplete), wrong calculations (mean or range), shape not described or vague, outliers missed.
Question 12
The ages (in years) of students in a club are: 10, 11, 12, 20, 21, 22. Which choice best describes the distribution using center, spread, and shape?
- Center: 16; Spread: range 22−10=12; Shape: two clusters (10–12 and 20–22) with a gap from 13–19. (correct answer)
- Center: 10; Spread: range 12; Shape: symmetric because the values increase by 1.
- Center: 16; Spread: 6; Shape: two clusters but no gaps.
- Center: 22; Spread: range 12; Shape: skewed left because the smallest value is 10.
Explanation: This question tests understanding of data distribution characterized by three features: center (typical value like mean/median), spread (variability like range), and overall shape (pattern: symmetric, skewed, clusters, outliers). Distribution characteristics: (1) center describes typical value (where middle is: mean=sum/count, median=middle value when ordered, shows what's typical in data), (2) spread describes variability (how spread out: range=max-min, shows how much values differ), (3) shape describes overall pattern (symmetric: mirror around center, skewed: long tail one direction, clusters: groups separated by gaps, outliers: values far from rest); all three needed for complete description: center alone doesn't tell variability, spread alone doesn't tell typical value, shape shows distribution pattern (together give full picture). For example, test scores 50,52,53,54,55,80, describe: center median=53.5 (typical score, middle of ordered data, resistant to outlier 80), spread range=80-50=30 (scores vary by 30 points, or without outlier: range 5, outlier inflates spread), shape: skewed right with outlier (most scores 50-55 clustered, one high outlier 80 pulls right, not symmetric); or ages 10,12,14,15,16,18,20: center mean=15 median=15 (both at middle), spread range=10 (ages vary 10 years), shape symmetric (values roughly even both sides of 15). The correct description is center at 16, spread with range 22-10=12, and shape with two clusters (10–12 and 20–22) with a gap from 13–19. Errors in other choices include wrong center like 10 or 22, incorrect spread like 6 instead of 12, wrong shape like symmetric or skewed left when there are clear clusters and a gap, and missing the gap in description. To describe distributions: (1) find center (calculate mean or median: median better with outliers, mean sensitive to extremes), (2) find spread (range=max-min simple for grade 6, or estimate variability visually), (3) describe shape (look at data: symmetric? skewed which way? any outliers far from rest? clusters or gaps?), (4) combine (distribution has center X, spread Y, shape Z—complete picture). Understanding: center tells 'where' (typical location), spread tells 'how much variability' (tight cluster vs wide spread), shape tells 'what pattern' (symmetric bell, skewed with tail, bimodal with two peaks, etc.); example data: 10,11,12,20,21,22 shows center≈16 (middle), spread≈12 (range 22-10), shape: two clusters (10-12 and 20-22 groups, gap 13-19 between); mistakes: describing only one or two characteristics (incomplete), wrong calculations (mean or range), shape not described or vague, outliers missed.
Question 13
Six students measured their resting heart rates (beats per minute): 50, 52, 53, 54, 55, 80. Which choice best describes the distribution using center, spread, and shape?
- Center: median =53.5; Spread: range 80−50=30; Shape: skewed right with an outlier at 80. (correct answer)
- Center: median =53.5; Spread: range 80−50=20; Shape: symmetric with no outliers.
- Center: mean ≈57.3; Spread: range 80−50=30; Shape: symmetric because there are 6 values.
- Center: 80; Spread: range 30; Shape: skewed left with an outlier at 50.
Explanation: This question tests understanding of data distribution characterized by three features: center (typical value like mean/median), spread (variability like range), and overall shape (pattern: symmetric, skewed, clusters, outliers). Distribution characteristics: (1) center describes typical value (where middle is: mean=sum/count, median=middle value when ordered, shows what's typical in data), (2) spread describes variability (how spread out: range=max-min, shows how much values differ), (3) shape describes overall pattern (symmetric: mirror around center, skewed: long tail one direction, clusters: groups separated by gaps, outliers: values far from rest); all three needed for complete description: center alone doesn't tell variability, spread alone doesn't tell typical value, shape shows distribution pattern (together give full picture). For example, test scores 50,52,53,54,55,80, describe: center median=53.5 (typical score, middle of ordered data, resistant to outlier 80), spread range=80-50=30 (scores vary by 30 points, or without outlier: range 5, outlier inflates spread), shape: skewed right with outlier (most scores 50-55 clustered, one high outlier 80 pulls right, not symmetric); or ages 10,12,14,15,16,18,20: center mean=15 median=15 (both at middle), spread range=10 (ages vary 10 years), shape symmetric (values roughly even both sides of 15). The correct description is center at median=53.5, spread with range 80-50=30, and shape skewed right with an outlier at 80. Errors in other choices include using mean ≈57.3 but claiming symmetric when skewed, wrong center like 80, incorrect spread like 20 instead of 30, wrong shape like skewed left or symmetric with no outliers when there is skewness and an outlier. To describe distributions: (1) find center (calculate mean or median: median better with outliers, mean sensitive to extremes), (2) find spread (range=max-min simple for grade 6, or estimate variability visually), (3) describe shape (look at data: symmetric? skewed which way? any outliers far from rest? clusters or gaps?), (4) combine (distribution has center X, spread Y, shape Z—complete picture). Understanding: center tells 'where' (typical location), spread tells 'how much variability' (tight cluster vs wide spread), shape tells 'what pattern' (symmetric bell, skewed with tail, bimodal with two peaks, etc.); example data: 10,11,12,20,21,22 shows center≈16 (middle), spread≈12 (range 22-10), shape: two clusters (10-12 and 20-22 groups, gap 13-19 between); mistakes: describing only one or two characteristics (incomplete), wrong calculations (mean or range), shape not described or vague, outliers missed.
Question 14
The heights (in cm) of 8 students are: 150, 152, 153, 154, 154, 155, 156, 170. What is the spread of the data using the range?
- 156−150=6
- 155−153=2
- 170−152=18
- 170−150=20 (correct answer)
Explanation: This question tests understanding of data distribution characterized by three features: center (typical value like mean/median), spread (variability like range), and overall shape (pattern: symmetric, skewed, clusters, outliers). Distribution characteristics: (1) center describes typical value (where middle is: mean=sum/count, median=middle value when ordered, shows what's typical in data), (2) spread describes variability (how spread out: range=max-min, shows how much values differ), (3) shape describes overall pattern (symmetric: mirror around center, skewed: long tail one direction, clusters: groups separated by gaps, outliers: values far from rest); all three needed for complete description: center alone doesn't tell variability, spread alone doesn't tell typical value, shape shows distribution pattern (together give full picture). For example, test scores 50,52,53,54,55,80, describe: center median=53.5 (typical score, middle of ordered data, resistant to outlier 80), spread range=80-50=30 (scores vary by 30 points, or without outlier: range 5, outlier inflates spread), shape: skewed right with outlier (most scores 50-55 clustered, one high outlier 80 pulls right, not symmetric); or ages 10,12,14,15,16,18,20: center mean=15 median=15 (both at middle), spread range=10 (ages vary 10 years), shape symmetric (values roughly even both sides of 15). The correct spread is the range 170-150=20, which captures the full variability from minimum to maximum, including the outlier at 170. Errors in other choices include calculating partial ranges like 170-152=18 or 156-150=6 or 155-153=2, which ignore the full extent of the data. To describe distributions: (1) find center (calculate mean or median: median better with outliers, mean sensitive to extremes), (2) find spread (range=max-min simple for grade 6, or estimate variability visually), (3) describe shape (look at data: symmetric? skewed which way? any outliers far from rest? clusters or gaps?), (4) combine (distribution has center X, spread Y, shape Z—complete picture). Understanding: center tells 'where' (typical location), spread tells 'how much variability' (tight cluster vs wide spread), shape tells 'what pattern' (symmetric bell, skewed with tail, bimodal with two peaks, etc.); example data: 10,11,12,20,21,22 shows center≈16 (middle), spread≈12 (range 22-10), shape: two clusters (10-12 and 20-22 groups, gap 13-19 between); mistakes: describing only one or two characteristics (incomplete), wrong calculations (mean or range), shape not described or vague, outliers missed.
Question 15
Ten test scores (out of 100) are shown: 72, 74, 74, 75, 76, 76, 77, 78, 78, 79. Which value is the range (a measure of spread) for these scores?
- 72
- 7 (correct answer)
- 79
- 75
Explanation: This question tests understanding data distribution characterized by three features: center (typical value like mean/median), spread (variability like range), and overall shape (pattern: symmetric, skewed, clusters, outliers). Distribution characteristics: (1) center describes typical value (where middle is: mean=sum/count, median=middle value when ordered, shows what's typical in data), (2) spread describes variability (how spread out: range=max-min, shows how much values differ), (3) shape describes overall pattern (symmetric: mirror around center, skewed: long tail one direction, clusters: groups separated by gaps, outliers: values far from rest). All three needed for complete description: center alone doesn't tell variability, spread alone doesn't tell typical value, shape shows distribution pattern (together give full picture). For example, test scores 50,52,53,54,55,80, describe: center median=53.5 (typical score, middle of ordered data, resistant to outlier 80), spread range=80-50=30 (scores vary by 30 points, or without outlier: range 5, outlier inflates spread), shape: skewed right with outlier (most scores 50-55 clustered, one high outlier 80 pulls right, not symmetric); or ages 10,12,14,15,16,18,20: center mean=15 median=15 (both at middle), spread range=10 (ages vary 10 years), shape symmetric (values roughly even both sides of 15). The correct range (spread) is 7, calculated as max 79 minus min 72. Incorrect choices might list other values like 75 or 79 (confusing with median or max) or 72 (the min). Describing: (1) find center (calculate mean or median: median better with outliers, mean sensitive to extremes), (2) find spread (range=max-min simple for grade 6, or estimate variability visually), (3) describe shape (look at data: symmetric? skewed which way? any outliers far from rest? clusters or gaps?), (4) combine (distribution has center X, spread Y, shape Z—complete picture). Understanding: center tells "where" (typical location), spread tells "how much variability" (tight cluster vs wide spread), shape tells "what pattern" (symmetric bell, skewed with tail, bimodal with two peaks, etc.). Example data: 10,11,12,20,21,22 shows center≈16 (middle), spread≈12 (range 22-10), shape: two clusters (10-12 and 20-22 groups, gap 13-19 between). Mistakes: describing only one or two characteristics (incomplete), wrong calculations (mean or range), shape not described or vague, outliers missed.
Question 16
A science class recorded the number of seeds that sprouted in 9 cups: 1, 2, 2, 3, 3, 3, 4, 4, 9. Which statement best describes the shape of this distribution?
- Skewed right because most values are small and 9 is far to the right (correct answer)
- Perfectly symmetric around 3
- Skewed left because most values are small
- Two clusters with a gap between 5 and 8
Explanation: This question tests understanding data distribution characterized by three features: center (typical value like mean/median), spread (variability like range), and overall shape (pattern: symmetric, skewed, clusters, outliers). Distribution characteristics: (1) center describes typical value (where middle is: mean=sum/count, median=middle value when ordered, shows what's typical in data), (2) spread describes variability (how spread out: range=max-min, shows how much values differ), (3) shape describes overall pattern (symmetric: mirror around center, skewed: long tail one direction, clusters: groups separated by gaps, outliers: values far from rest). All three needed for complete description: center alone doesn't tell variability, spread alone doesn't tell typical value, shape shows distribution pattern (together give full picture). For example, test scores 50,52,53,54,55,80, describe: center median=53.5 (typical score, middle of ordered data, resistant to outlier 80), spread range=80-50=30 (scores vary by 30 points, or without outlier: range 5, outlier inflates spread), shape: skewed right with outlier (most scores 50-55 clustered, one high outlier 80 pulls right, not symmetric); or ages 10,12,14,15,16,18,20: center mean=15 median=15 (both at middle), spread range=10 (ages vary 10 years), shape symmetric (values roughly even both sides of 15). The correct shape description is skewed right because most values are small and 9 is far to the right, creating a long tail. Incorrect choices might claim skewed left (wrong direction), perfectly symmetric (ignoring tail), or two clusters (no gap present). Describing: (1) find center (calculate mean or median: median better with outliers, mean sensitive to extremes), (2) find spread (range=max-min simple for grade 6, or estimate variability visually), (3) describe shape (look at data: symmetric? skewed which way? any outliers far from rest? clusters or gaps?), (4) combine (distribution has center X, spread Y, shape Z—complete picture). Understanding: center tells "where" (typical location), spread tells "how much variability" (tight cluster vs wide spread), shape tells "what pattern" (symmetric bell, skewed with tail, bimodal with two peaks, etc.). Example data: 10,11,12,20,21,22 shows center≈16 (middle), spread≈12 (range 22-10), shape: two clusters (10-12 and 20-22 groups, gap 13-19 between). Mistakes: describing only one or two characteristics (incomplete), wrong calculations (mean or range), shape not described or vague, outliers missed.
Question 17
Two groups tracked minutes spent reading in one evening.
Group A: 20, 22, 24, 26, 28, 30
Group B: 10, 12, 12, 13, 13, 40
Which choice correctly compares the distributions using center, spread, and shape?
- Group A: center 30; Group B: center 40; both are uniform
- Group A: center about 25, smaller spread, roughly symmetric; Group B: center about 12.5 (median), larger spread, skewed right due to 40 (correct answer)
- Group A and Group B have the same center, spread, and shape
- Group A: skewed right; Group B: symmetric; both have range 10
Explanation: This question tests understanding data distribution characterized by three features: center (typical value like mean/median), spread (variability like range), and overall shape (pattern: symmetric, skewed, clusters, outliers). Distribution characteristics: (1) center describes typical value (where middle is: mean=sum/count, median=middle value when ordered, shows what's typical in data), (2) spread describes variability (how spread out: range=max-min, shows how much values differ), (3) shape describes overall pattern (symmetric: mirror around center, skewed: long tail one direction, clusters: groups separated by gaps, outliers: values far from rest). All three needed for complete description: center alone doesn't tell variability, spread alone doesn't tell typical value, shape shows distribution pattern (together give full picture). For example, test scores 50,52,53,54,55,80, describe: center median=53.5 (typical score, middle of ordered data, resistant to outlier 80), spread range=80-50=30 (scores vary by 30 points, or without outlier: range 5, outlier inflates spread), shape: skewed right with outlier (most scores 50-55 clustered, one high outlier 80 pulls right, not symmetric); or ages 10,12,14,15,16,18,20: center mean=15 median=15 (both at middle), spread range=10 (ages vary 10 years), shape symmetric (values roughly even both sides of 15). The correct comparison is Group A with center about 25, smaller spread, roughly symmetric; Group B with center about 12.5 (median), larger spread, skewed right due to 40. Incorrect choices might claim same characteristics (they differ), wrong shapes like Group A skewed right, or incorrect centers like 30 or 40. Describing: (1) find center (calculate mean or median: median better with outliers, mean sensitive to extremes), (2) find spread (range=max-min simple for grade 6, or estimate variability visually), (3) describe shape (look at data: symmetric? skewed which way? any outliers far from rest? clusters or gaps?), (4) combine (distribution has center X, spread Y, shape Z—complete picture). Understanding: center tells "where" (typical location), spread tells "how much variability" (tight cluster vs wide spread), shape tells "what pattern" (symmetric bell, skewed with tail, bimodal with two peaks, etc.). Example data: 10,11,12,20,21,22 shows center≈16 (middle), spread≈12 (range 22-10), shape: two clusters (10-12 and 20-22 groups, gap 13-19 between). Mistakes: describing only one or two characteristics (incomplete), wrong calculations (mean or range), shape not described or vague, outliers missed.
Question 18
Data Set A (number of songs in playlists) is: 14, 15, 15, 16, 16, 17, 17, 18. Data Set B is: 10, 11, 12, 13, 14, 15, 16, 30. Which comparison is most accurate?
- Set A has two clusters; Set B has no outliers
- Both sets have the same center and the same spread, and both are symmetric
- Set A is skewed right because it has 18; Set B is symmetric because it has values from 10 to 30
- Set A has a center around 16 and small spread; Set B has a center around 13.5 and a much larger spread because of 30, making it skewed right (correct answer)
Explanation: This question tests understanding of data distribution characterized by three features: center (typical value like mean/median), spread (variability like range), and overall shape (pattern: symmetric, skewed, clusters, outliers), by comparing two sets. Distribution characteristics: (1) center describes typical value (where middle is: mean=sum/count, median=middle value when ordered, shows what's typical in data), (2) spread describes variability (how spread out: range=max-min, shows how much values differ), (3) shape describes overall pattern (symmetric: mirror around center, skewed: long tail one direction, clusters: groups separated by gaps, outliers: values far from rest). All three needed for complete description: center alone doesn't tell variability, spread alone doesn't tell typical value, shape shows distribution pattern (together give full picture). The most accurate comparison is Set A has a center around 16 and small spread; Set B has a center around 13.5 and a much larger spread because of 30, making it skewed right. Common errors include claiming same center/spread/shape, misidentifying skew direction, or saying A has clusters when it's symmetric. To describe: (1) find center (calculate mean or median: median better with outliers, mean sensitive to extremes), (2) find spread (range=max-min simple for grade 6, or estimate variability visually), (3) describe shape (look at data: symmetric? skewed which way? any outliers far from rest? clusters or gaps?), (4) combine (distribution has center X, spread Y, shape Z—complete picture). Understanding: center tells 'where' (typical location), spread tells 'how much variability' (tight cluster vs wide spread), shape tells 'what pattern' (symmetric bell, skewed with tail, bimodal with two peaks, etc.); comparing sets highlights differences in all three.
Question 19
A student recorded how many minutes it took to finish a warm-up lap on 9 different days: 6, 6, 7, 7, 7, 8, 8, 9, 14. Which choice best describes the shape of the distribution?
- Skewed right, because most values are between 6 and 9 with a high value (14) stretching the right side (correct answer)
- Skewed left, because most values are high with a few low values
- Two clusters with a gap, because there is a break between 7 and 8
- Roughly symmetric, because the values are evenly spread from 6 to 14
Explanation: This question tests understanding of data distribution characterized by three features: center (typical value like mean/median), spread (variability like range), and overall shape (pattern: symmetric, skewed, clusters, outliers), focusing here on shape. Distribution characteristics: (1) center describes typical value (where middle is: mean=sum/count, median=middle value when ordered, shows what's typical in data), (2) spread describes variability (how spread out: range=max-min, shows how much values differ), (3) shape describes overall pattern (symmetric: mirror around center, skewed: long tail one direction, clusters: groups separated by gaps, outliers: values far from rest). All three needed for complete description: center alone doesn't tell variability, spread alone doesn't tell typical value, shape shows distribution pattern (together give full picture); for example, in this data (6,6,7,7,7,8,8,9,14), most values cluster low with a high tail, showing right skew. The correct description of shape is skewed right, because most values are between 6 and 9 with a high value (14) stretching the right side. Common errors include claiming skewed left (reversing direction), symmetric (ignoring tail), or two clusters (no real gap). To describe: (1) find center (calculate mean or median: median better with outliers, mean sensitive to extremes), (2) find spread (range=max-min simple for grade 6, or estimate variability visually), (3) describe shape (look at data: symmetric? skewed which way? any outliers far from rest? clusters or gaps?), (4) combine (distribution has center X, spread Y, shape Z—complete picture). Understanding: center tells 'where' (typical location), spread tells 'how much variability' (tight cluster vs wide spread), shape tells 'what pattern' (symmetric bell, skewed with tail, bimodal with two peaks, etc.); identifying skew direction is key for patterns like this.
Question 20
The test scores (out of 100) for 10 students are: 61, 63, 64, 65, 66, 67, 68, 69, 70, 92. What is the best description of the center of this data set?
- The center is 92 because it is the largest score
- The center is 61 because it is the smallest score
- The mean must equal 92 because 92 is an outlier
- The median is 66.5, which is a good typical value because it is not pulled toward 92 (correct answer)
Explanation: This question tests understanding of data distribution characterized by three features: center (typical value like mean/median), spread (variability like range), and overall shape (pattern: symmetric, skewed, clusters, outliers), focusing here on center. Distribution characteristics: (1) center describes typical value (where middle is: mean=sum/count, median=middle value when ordered, shows what's typical in data), (2) spread describes variability (how spread out: range=max-min, shows how much values differ), (3) shape describes overall pattern (symmetric: mirror around center, skewed: long tail one direction, clusters: groups separated by gaps, outliers: values far from rest). All three needed for complete description: center alone doesn't tell variability, spread alone doesn't tell typical value, shape shows distribution pattern (together give full picture); for example, in this data (61,63,64,65,66,67,68,69,70,92), median=66.5 is better than mean≈67.5 due to outlier pulling it up. The correct description of center is the median 66.5, which is a good typical value because it is not pulled toward 92. Common errors include claiming center is 92 (maximum) or 61 (minimum), or saying mean must equal 92 due to outlier, ignoring median's resistance to extremes. To describe: (1) find center (calculate mean or median: median better with outliers, mean sensitive to extremes), (2) find spread (range=max-min simple for grade 6, or estimate variability visually), (3) describe shape (look at data: symmetric? skewed which way? any outliers far from rest? clusters or gaps?), (4) combine (distribution has center X, spread Y, shape Z—complete picture). Understanding: center tells 'where' (typical location), spread tells 'how much variability' (tight cluster vs wide spread), shape tells 'what pattern' (symmetric bell, skewed with tail, bimodal with two peaks, etc.); mistakes like focusing only on extremes miss the typical value.