Question 1

A researcher collects the daily screen times (in minutes) for 30 adults and wants to create a frequency distribution with 6 classes. The minimum value is 120 and the maximum is 330. What is the appropriate class width to use?

Accepted Answer

$$\frac{330-120}{6} = 35 ($$rounded up to 36)$

Question 2

Which of the following best describes a frequency polygon?

Accepted Answer

A line graph that emphasizes the continuous change in frequencies by connecting class midpoints.

Question 3

Given a class with a lower class limit of 50 and an upper class limit of 69, what is the midpoint of this class?

Accepted Answer

$$\frac{50+69}{2} = 59.5$$

Question 4

A frequency distribution for exam scores is constructed with the following classes: 40-49, 50-59, 60-69, 70-79, 80-89. What is the class width?

Accepted Answer

$$50-40 = 10$$

Question 5

If a class in a frequency distribution has a frequency of 8 and the total sample size is 40, what is the relative frequency of this class?

Accepted Answer

$$\frac{8}{40} = 0.2$$

Question 6

Which of the following statements about class boundaries is correct?

Accepted Answer

Class boundaries are used to ensure that bars in a histogram touch by eliminating gaps between classes.

Question 7

A cumulative frequency graph (ogive) is constructed by plotting cumulative frequencies at which points?

Accepted Answer

At the upper class boundaries.

Question 8

A data set has a minimum value of 22 and a maximum value of 97. If you want to create 8 classes, what is the correct class width to use?

Accepted Answer

$$\frac{97-22}{8} = 9.375 ($$rounded up to 10)$

Question 9

In a frequency histogram, what does the height of each bar represent?

Accepted Answer

The frequency of the class.

Question 10

A class in a frequency distribution has a lower class limit of 100 and an upper class limit of 119. What are the class boundaries?

Accepted Answer

$$99.5$$ and $$119.5$$

Question 11

Which of the following is NOT a step in constructing a frequency distribution?

Accepted Answer

Calculate the mean of the data.

Question 12

A relative frequency histogram differs from a frequency histogram in which way?

Accepted Answer

The vertical axis shows relative frequencies instead of actual frequencies.

Question 13

If the cumulative frequency for the last class in a distribution is 50, what is the sample size?

Accepted Answer

It is equal to 50.

Question 14

A frequency distribution for the number of hours worked per week by employees is constructed. The class 30-39 has a frequency of 12, and the cumulative frequency up to this class is 25. What does this mean?

Accepted Answer

12 employees worked between 30 and 39 hours, and 25 employees worked 39 hours or less.

Question 15

Which of the following best describes the purpose of using class midpoints in frequency polygons?

Accepted Answer

To plot the points that are connected to form the frequency polygon.

Question 16

A data set of cholesterol levels is grouped into classes with a width of 20. The first class is 120-139. What is the lower class limit of the third class?

Accepted Answer

$$120 + 2 	imes 20 = 160$$

Question 17

In a real-world scenario, a hospital records the number of patients admitted each day for a month. Which type of graph would best show the cumulative number of patients admitted up to each day?

Accepted Answer

Ogive

Question 18

A frequency distribution for the number of books read by students in a semester is as follows: 0-2 (5 students), 3-5 (8 students), 6-8 (12 students), 9-11 (10 students). What is the cumulative frequency for the class 6-8?

Accepted Answer

$$5 + 8 + 12 = 25$$

Question 19

A frequency histogram for the number of hours spent on social media per week shows that the tallest bar is for the class 10-14 hours. What does this indicate?

Accepted Answer

Most people spend between 10 and 14 hours per week on social media.

Descriptive Statistics: Frequency Distributions and Their Graphs

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