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

If the minimum value in a data set is 120 and the maximum value is 340, and you want to create 5 classes, what is the class width?

Accepted Answer

Class width $$= \frac{340 - 120}{5} = 44 ($$rounded up to 44)

Question 3

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

Accepted Answer

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

Question 4

A frequency distribution has the following frequencies for seven classes: 2, 4, 6, 8, 5, 3, 2. What is the cumulative frequency for the fifth class?

Accepted Answer

Cumulative frequency $$= 2 + 4 + 6 + 8 + 5 = 25$$

Question 5

Which of the following statements about histograms is TRUE?

Accepted Answer

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

Question 6

In constructing a frequency distribution, why is it important that classes do not overlap?

Accepted Answer

To ensure each data entry belongs to only one class.

Question 7

Given a class with lower class limit 150 and upper class limit 185, what are the class boundaries?

Accepted Answer

Lower boundary $$= 149.5$$, Upper boundary $$= 185.5$$

Question 8

Which type of graph would you use to display the cumulative frequency of each class at its upper class boundary?

Accepted Answer

Ogive

Question 9

If a frequency distribution has a sample size $$n = 30$$, what is the cumulative frequency of the last class?

Accepted Answer

Cumulative frequency $$= n = 30$$

Question 10

A relative frequency histogram is different from a frequency histogram because:

Accepted Answer

The vertical scale measures relative frequencies instead of frequencies.

Question 11

A data set has a minimum value of 155 and a maximum value of 405. If you want 7 classes, what is the range and what is the class width?

Accepted Answer

Range $$= 405 - 155 = 250$$, Class width $$= \frac{250}{7} \approx 36 ($$rounded up to 36)

Question 12

Which of the following best describes a frequency polygon?

Accepted Answer

A line graph that emphasizes the continuous change in frequencies.

Question 13

In a real-world scenario, a hospital records the number of minutes each patient spends in the waiting room. Which graph would best help the hospital visualize the percentage of patients in each time interval?

Accepted Answer

Relative frequency histogram

Question 14

If the cumulative frequency increases most rapidly between two classes, what does this indicate about the data?

Accepted Answer

A large number of data entries fall within that interval.

Question 15

A frequency histogram for cell phone screen times shows that two-thirds of adults spend more than 262.5 minutes per day. What statistical concept does this illustrate?

Accepted Answer

Interpretation of frequency distribution using real-world data.

Question 16

When constructing a frequency polygon, why should the graph begin and end on the horizontal axis?

Accepted Answer

To visually emphasize the continuous nature of the data and ensure the graph is closed.

Question 17

A class has a lower limit of 262 and an upper limit of 298. What is the midpoint of this class?

Accepted Answer

Midpoint $$= \frac{262 + 298}{2} = 280$$

Question 18

In a frequency distribution, what does the relative frequency of a class represent?

Accepted Answer

The portion or percentage of the data that falls in a particular class.

Question 19

A school wants to analyze the distribution of test scores. Which graph would best show how many students scored below a certain value?

Accepted Answer

Ogive

Descriptive Statistics: Frequency Distributions and Graphs

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