Data Displays - GED Math

1. What does a positive association in a scatterplot mean?

   As the $x$ values increase, the $y$ values tend to increase. The points rise from left to right.

2. Which type of display shows the parts of a whole as percentages?

   A circle graph (pie chart). Each sector's size is its share of the whole, and the sectors total $100\%$.

3. What does the height of each bar in a histogram show?

   The frequency: how many data values fall in that bar's interval.

4. A scatterplot's trend line is $y = 2x + 10$. What $y$ value does it predict when $x = 15$?

   $40$. Substitute: $2(15) + 10 = 40$.

5. What is an outlier in a scatterplot or data set?

   A value that lies far from the overall pattern of the rest of the data.

6. What does the slope of a trend line on a scatterplot represent?

   The predicted change in $y$ for each increase of $1$ in $x$.

7. What share of the data falls inside the box of a box plot?

   The middle $50\%$. The box spans the first quartile to the third quartile, a width called the interquartile range.

8. Which type of display best shows how one quantity changes over time?

   A line graph. Time goes on the horizontal axis, so rises and drops show change from one period to the next.

9. A circle graph sector has a central angle of $90^\circ$. What percent of the whole does it represent?

   $25\%$. A full circle is $360^\circ$, and $\frac{90}{360} = \frac{1}{4}$.

10. What does a negative association in a scatterplot look like?

    The points fall from left to right: as $x$ increases, $y$ tends to decrease.

11. What does the line inside the box of a box plot mark?

    The median. The box itself runs from the first quartile to the third quartile.

12. In a two-way table, $30$ adults live in rural areas and $12$ of them prefer tea. What is the probability a rural adult prefers tea?

    $0.4$. Use only the rural row as the total: $\frac{12}{30} = 0.4$.

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