$$\hat{y} = 80.9 + 3.22 \times 30 = 177.5$$

Question 1

Which of the following best describes the purpose of a frequency distribution in statistics?

Accepted Answer

To organize and summarize data by showing how data are partitioned among several categories or classes.

Question 2

Given a data set with a minimum value of 20 and a maximum value of 95, and you want to create 5 classes, what is the appropriate class width to use?

Accepted Answer

$$\frac{95 - 20}{5} = 15 ($$rounded up to 16)

Question 3

Which of the following is NOT a feature of a histogram?

Accepted Answer

It is used to compare categorical data.

Question 4

A histogram of exam scores is bell-shaped and symmetric. Which distribution shape does this represent?

Accepted Answer

Normal distribution

Question 5

If a histogram has a longer tail on the right side, how is the data described?

Accepted Answer

Skewed to the right (positively skewed)

Question 6

Which type of graph is most appropriate for displaying the frequencies of categories of qualitative data?

Accepted Answer

Bar graph

Question 7

A researcher wants to show the trend of average gas prices in the U.S. from 2000 to 2020. Which graph should they use?

Accepted Answer

Time-series graph

Question 8

Which of the following statements about a Pareto chart is TRUE?

Accepted Answer

It is a bar graph for categorical data with bars arranged in descending order of frequency.

Question 9

What is the main risk of using a pictograph to represent data?

Accepted Answer

It can exaggerate differences due to the use of area or volume instead of length.

Question 10

Which of the following best describes a scatterplot?

Accepted Answer

A plot of paired (x, y) quantitative data to reveal possible relationships.

Question 11

If the linear correlation coefficient $$r$$ for two variables is $$0.95$$, what does this indicate?

Accepted Answer

There is a strong positive linear correlation.

Question 12

Given the regression equation $$\hat{y} = 80.9 + 3.22x$$, what is the predicted value of $$y$$ when $$x = 30$$?

Accepted Answer

$$\hat{y} = 80.9 + 3.22 	imes 30 = 177.5$$

Question 13

Which of the following is a key feature of a stemplot?

Accepted Answer

It arranges data in order and allows the original data to be recovered.

Question 14

A cumulative frequency distribution is most useful for:

Accepted Answer

Displaying the sum of frequencies for each class and all previous classes.

Question 15

Which of the following is a common error that can make a graph misleading?

Accepted Answer

Using a nonzero vertical axis to exaggerate differences.

Question 16

A dotplot is particularly useful because:

Accepted Answer

It allows you to recreate the original list of data values.

Question 17

Which of the following best describes a relative frequency histogram?

Accepted Answer

It has the same shape as a histogram but the vertical axis shows relative frequencies.

Question 18

If a pie chart is used to display the results of a survey on favorite ice cream flavors, what does the size of each slice represent?

Accepted Answer

The proportion or percentage of responses for each flavor.

Question 19

Which of the following is the correct formula for the class midpoint?

Accepted Answer

$$	ext{Class Midpoint} = \frac{	ext{Lower Class Limit} + 	ext{Upper Class Limit}}{2}$$

Exploring Data with Tables and Graphs: Introductory Statistics CHAP 2

Study Guide - Practice Questions