Data-Based Predictions

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ISEE Lower Level: Quantitative Reasoning › Data-Based Predictions

Questions 1 - 10
1

In a video game, a player earns points based on a pattern. Level 1 earns 100 points. Level 2 earns 125 points. Level 3 earns 150 points. However, on any level that is a multiple of 5, the player earns a 75-point bonus. How many points will a player earn for completing Level 10?

350 points

375 points

325 points

400 points

Explanation

First, determine the base points pattern. The points increase by 25 for each level: Level 1 = 100, Level 2 = 125, Level 3 = 150. The pattern is 100 + 25 × (level - 1). For Level 10, the base points are 100 + 25 × (10 - 1) = 100 + 25 × 9 = 100 + 225 = 325 points. Since Level 10 is a multiple of 5, the player earns a 75-point bonus. Total points for Level 10: 325 + 75 = 400 points.

2

A rubber ball is dropped and its bounce height is measured. After the first bounce, it reaches 81 cm. After the second bounce, it reaches 27 cm. After the third bounce, it reaches 9 cm. If the pattern continues, what height will the ball reach after its fifth bounce?

3 cm

6 cm

0 cm

1 cm

Explanation

The pattern shows that the height of each bounce is one-third of the previous bounce height (81 / 3 = 27; 27 / 3 = 9). We need to find the height after the fifth bounce. Bounce 1: 81 cm. Bounce 2: 27 cm. Bounce 3: 9 cm. Bounce 4: 9 / 3 = 3 cm. Bounce 5: 3 / 3 = 1 cm.

3

In 2015, a small town's population was 2,400. In 2017, the population was 2,460. In 2019, the population was 2,520. If the population continues to grow at this constant rate, what is the predicted population for the year 2025?

2,760

2,820

2,640

2,700

Explanation

The population increases by 60 people every 2 years (2460 - 2400 = 60). This means the growth rate is 30 people per year. We want to predict the population in 2025. The last data point is 2,520 in 2019. The number of years from 2019 to 2025 is 6 years. The total growth will be 6 years * 30 people/year = 180 people. Add this growth to the 2019 population: 2,520 + 180 = 2,700.

4

A train is scheduled to depart at 7:10 AM, 7:25 AM, 7:40 AM, and 7:55 AM. If this schedule pattern continues, what is the predicted departure time of the fifth train after the 7:55 AM departure?

8:55 AM

9:20 AM

9:10 AM

8:40 AM

Explanation

The pattern shows the train departs every 15 minutes (7:25 - 7:10 = 15). The question asks for the fifth train after the 7:55 AM departure. We need to calculate the total time for 5 intervals: 5 * 15 minutes = 75 minutes. Add 75 minutes to 7:55 AM. 75 minutes is equal to 1 hour and 15 minutes. 7:55 AM + 1 hour is 8:55 AM. Then, 8:55 AM + 15 minutes is 9:10 AM.

5

A botanist records the height of a new plant. On the first day, it is 8 cm tall. On the second day, it is 13 cm tall. On the third day, it is 18 cm tall. If the plant continues to grow at the same rate, what will its height be on the seventh day?

38 cm

48 cm

43 cm

35 cm

Explanation

The plant's height increases by 5 cm each day (13 - 8 = 5; 18 - 13 = 5). We can find the height on the seventh day by continuing the pattern. Day 1: 8 cm. Day 2: 13 cm. Day 3: 18 cm. Day 4: 23 cm. Day 5: 28 cm. Day 6: 33 cm. Day 7: 38 cm. Alternatively, the growth over 6 days (from day 1 to day 7) is 6 * 5 = 30 cm. The final height is the initial height plus the growth: 8 cm + 30 cm = 38 cm.

6

Maya starts a savings plan. In the first month, she saves $4. In the second month, she saves $7. In the third month, she saves $10. If she continues this pattern, how much money will she have saved in total after five months?

$35

$45

$50

$65

Explanation

The amount Maya saves each month follows a pattern: she saves $3 more than the previous month (7-4=3; 10-7=3). Month 1: $4. Month 2: $7. Month 3: $10. Month 4: $10 + $3 = $13. Month 5: $13 + $3 = $16. The total amount saved after five months is: $4 + $7 + $10 + $13 + $16 = $50.

7

A box contains 128 apples. On the first day, half of the apples are sold. On the second day, half of the remaining apples are sold. If this pattern continues, how many apples will be left in the box at the end of the fourth day?

8 apples

32 apples

16 apples

4 apples

Explanation

This problem tests your understanding of repeated percentage changes, specifically when the same fraction is removed multiple times. When you see "half of the remaining" repeatedly, you're dealing with exponential decay where the amount keeps getting cut in half.

Let's trace through each day systematically. Starting with 128 apples:

Day 1: Half are sold, so $$128 ÷ 2 = 64$$ apples remain

Day 2: Half of the remaining 64 are sold, so $$64 ÷ 2 = 32$$ apples remain

Day 3: Half of the remaining 32 are sold, so $$32 ÷ 2 = 16$$ apples remain

Day 4: Half of the remaining 16 are sold, so $$16 ÷ 2 = 8$$ apples remain

You can also think of this as multiplying by $$\frac{1}{2}$$ four times: $$128 × (\frac{1}{2})^4 = 128 × \frac{1}{16} = 8$$.

Looking at the wrong answers: (A) 4 apples would be the result after 5 days, not 4 days. (B) 32 apples is what remains after only 2 days. (C) 16 apples is what remains after 3 days, missing the fourth day entirely.

Each wrong answer represents stopping the calculation one day too early or going one day too far, which are common mistakes when tracking multi-step processes.

For problems involving repeated halvings or doubling, always count your steps carefully and consider writing out each day individually before looking for shortcuts. The pattern $$\text{original amount} × (\frac{1}{2})^n$$ can save time once you're confident with the concept.

8

A pet store is building a display of fish tanks. The bottom row has 12 tanks. The row above it has 10 tanks. The row above that has 8 tanks. The pattern continues until the top row has only 2 tanks. How many rows of tanks are in the entire display?

7 rows

5 rows

6 rows

10 rows

Explanation

This question tests your ability to recognize and work with arithmetic sequences - patterns where numbers change by the same amount each time.

When you see the tanks arranged as 12, 10, 8, and continuing down to 2, you're looking at a sequence that decreases by 2 each row. To find how many rows there are, you need to count how many numbers are in this sequence.

Starting from 12 and subtracting 2 each time: 12, 10, 8, 6, 4, 2. Count these terms: that's 6 rows total. You can also think of this algebraically - if the bottom row is 12 and each row has 2 fewer tanks, then row $$n$$ (counting from the bottom) has $$12 - 2(n-1)$$ tanks. When the top row has 2 tanks, you solve: $$2 = 12 - 2(n-1)$$, which gives you $$n = 6$$.

Looking at the wrong answers: (A) 5 rows would mean stopping at 4 tanks instead of continuing to 2 tanks. (B) 10 rows incorrectly assumes the pattern decreases by 1 each row rather than 2, giving you 10 steps from 12 down to 2. (C) 7 rows might come from miscounting or including an extra row that doesn't follow the pattern.

When working with sequence problems, always write out the terms systematically and count carefully. Don't try to do too much mental math - listing "12, 10, 8, 6, 4, 2" on paper prevents counting errors and makes the pattern crystal clear.

9

A hiker is climbing a mountain. She starts at an elevation of 200 feet. After one hour, she is at 550 feet. After two hours, she is at 900 feet. If she continues to climb at this constant rate, what will her elevation be after four hours of hiking?

1250 feet

1750 feet

1600 feet

1400 feet

Explanation

When you encounter a problem about constant rates of change, you're working with linear relationships. The key is to identify the pattern and use it to predict future values.

Let's find the hiker's rate of climbing. From her starting elevation of 200 feet, she reaches 550 feet after one hour. That's an increase of $$550 - 200 = 350$$ feet in one hour. After two hours, she's at 900 feet, which is another increase of $$900 - 550 = 350$$ feet. This confirms she's climbing at a constant rate of 350 feet per hour.

To find her elevation after four hours, add the total distance climbed to her starting point: $$200 + (4 \times 350) = 200 + 1400 = 1600$$ feet. This makes A) 1600 feet correct.

Looking at the wrong answers: B) 1400 feet represents a common error where students forget to add the starting elevation and only calculate the total distance climbed. C) 1250 feet might result from miscalculating the rate as 262.5 feet per hour (if you divided the total elevation change by the wrong time interval). D) 1750 feet could come from adding an extra hour's worth of climbing or making an arithmetic error.

Remember that in constant rate problems, always identify the rate first, then multiply by the total time, and finally add any starting value. Don't forget that "starting point plus change" is the standard formula for these linear growth scenarios.

10

A baker uses a special yeast that triples in volume every hour. She starts with 10 cubic centimeters of yeast at 8:00 AM. At 9:00 AM, she has 30 cubic centimeters. At 10:00 AM, she has 90 cubic centimeters. If the pattern continues, how much yeast will she have at 12:00 PM?

810 cubic centimeters

540 cubic centimeters

270 cubic centimeters

900 cubic centimeters

Explanation

This question tests exponential growth, where a quantity multiplies by the same factor repeatedly over equal time periods. When you see words like "triples," "doubles," or "grows by a factor of," you're dealing with exponential patterns rather than simple addition.

Let's trace the yeast volume hour by hour. Starting with 10 cubic centimeters at 8:00 AM, the yeast triples each hour:

  • 8:00 AM: 10 cm³
  • 9:00 AM: 10 × 3 = 30 cm³
  • 10:00 AM: 30 × 3 = 90 cm³
  • 11:00 AM: 90 × 3 = 270 cm³
  • 12:00 PM: 270 × 3 = 810 cm³

You can also use the exponential formula: $$\text{Final amount} = \text{Initial amount} \times 3^{\text{number of hours}}$$. From 8:00 AM to 12:00 PM is 4 hours, so: $$10 \times 3^4 = 10 \times 81 = 810$$ cubic centimeters.

Looking at the wrong answers: B) 540 represents multiplying by 3 only three times instead of four—a common error when students miscount the time intervals. C) 270 is the amount at 11:00 AM, stopping one hour too early. D) 900 might result from incorrectly adding rather than multiplying, or miscalculating $$3^4$$.

When solving exponential growth problems, always count your time intervals carefully and remember that the quantity gets multiplied by the growth factor for each complete time period. Drawing a simple timeline can help you avoid off-by-one errors.

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