Question 1

Which of the following best describes a frequency distribution?

Accepted Answer

A table that shows classes or intervals of data with a count of the number of entries in each class.

Question 2

Given a data set with a minimum value of 120 and a maximum value of 340, and you want to create 8 classes, what is the appropriate class width?

Accepted Answer

$$\frac{340 - 120}{8} = 27.5$$, so round up to 28

Question 3

What is the formula for the midpoint of a class with lower class limit $$L$$ and upper class limit $$U$$?

Accepted Answer

$$\frac{L + U}{2}$$

Question 4

If a class in a frequency distribution has a frequency of 8 and the total number of data entries is 40, what is the relative frequency of the class?

Accepted Answer

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

Question 5

Which of the following statements about histograms is TRUE?

Accepted Answer

The bars in a histogram must touch because the data is continuous.

Question 6

A cumulative frequency graph (ogive) is constructed by plotting which of the following?

Accepted Answer

Upper class boundaries and their corresponding cumulative frequencies.

Question 7

If the cumulative frequency for the third class is 18 and for the fourth class is 25, what is the frequency of the fourth class?

Accepted Answer

$$25 - 18 = 7$$

Question 8

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

Accepted Answer

Calculate the mean and median of the data set.

Question 9

In a frequency polygon, what is plotted on the horizontal axis?

Accepted Answer

Class midpoints

Question 10

A data set of exam scores is grouped into the following classes: 50-59, 60-69, 70-79, 80-89, 90-99. What is the class width?

Accepted Answer

$$60 - 50 = 10$$

Question 11

Why are class boundaries used when constructing a histogram?

Accepted Answer

To ensure that consecutive bars touch, representing continuous data.

Question 12

If a frequency distribution has the following frequencies for five classes: 3, 7, 12, 8, 5, what is the cumulative frequency for the fourth class?

Accepted Answer

$$3 + 7 + 12 + 8 = 30$$

Question 13

Which of the following best describes a relative frequency histogram?

Accepted Answer

A histogram where the vertical axis shows the proportion or percentage of data in each class.

Question 14

A researcher collects the following data on daily water consumption (in liters) for 20 households: 120, 135, 140, 150, 155, 160, 165, 170, 175, 180, 185, 190, 195, 200, 205, 210, 215, 220, 225, 230. If the researcher wants to create 5 classes, what is the class width?

Accepted Answer

$$\frac{230 - 120}{5} = 22$$, so round up to 22

Question 15

Which of the following is a correct interpretation of a steep segment in an ogive?

Accepted Answer

A large number of data values fall within that class interval.

Descriptive Statistics: Frequency Distributions and Graphs

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