Q: What is the formula for finding the class midpoint?

$$\frac{\text{Lower class limit} + \text{Upper class limit}}{2}$$

Question 1

Which of the following best describes a frequency distribution?

Accepted Answer

A table that shows how data are partitioned among several categories (or classes) by listing the categories along with the number (frequency) of data values in each of them.

Question 2

How is the class width calculated when constructing a frequency distribution?

Accepted Answer

By subtracting the smallest data value from the largest and dividing by the number of classes, then rounding up.

Question 3

Given the following lower class limits: 75, 125, 175, 225, 275, what is the class width?

Accepted Answer

$$50$$

Question 4

What is the formula for finding the class midpoint?

Accepted Answer

$$\frac{	ext{Lower class limit} + 	ext{Upper class limit}}{2}$$

Question 5

A cumulative frequency distribution for McDonald's lunch service times shows 35 for 'Less than 175 seconds.' What does this number represent?

Accepted Answer

The total number of service times less than or equal to 175 seconds.

Question 6

If a frequency distribution has a large gap between two groups of data, what might this indicate?

Accepted Answer

There are two or more different populations in the data.

Question 7

Which of the following is NOT a characteristic of a normal distribution as seen in a frequency distribution?

Accepted Answer

There are large gaps between classes.

Question 8

Given the following frequency distribution for McDonald's lunch service times: 75–124 sec: 11, 125–174 sec: 24, 175–224 sec: 10, 225–274 sec: 3, 275–324 sec: 2. What is the relative frequency for the class 125–174 seconds?

Accepted Answer

$$\frac{24}{50} = 0.48$$

Question 9

Why is it important to round up the class width when constructing a frequency distribution?

Accepted Answer

To ensure all data values are included in the classes.

Question 10

In a relative frequency distribution, what should the sum of all percentages be?

Accepted Answer

$$100\%$$

Question 11

If you are comparing the drive-through service times at McDonald's and Dunkin' Donuts using relative frequency distributions, what is the main advantage?

Accepted Answer

It allows for easy comparison of the proportions of service times in each class between the two restaurants.

Question 12

Which of the following best describes class boundaries?

Accepted Answer

Numbers used to separate the classes, but without the gaps created by class limits.

Question 13

Suppose you have a data set with a minimum value of 83 and you want to construct a frequency distribution with 5 classes and a class width of 50. What should you choose as the first lower class limit?

Accepted Answer

A convenient value below 83, such as 75.

Question 14

Which of the following is a correct step in constructing a frequency distribution?

Accepted Answer

List the lower class limits in a vertical column and then determine and enter the upper class limits.

Question 15

A frequency distribution of penny weights shows a large gap between two groups. What real-world explanation does the textbook provide for this?

Accepted Answer

Pennies made before and after 1983 have different metal compositions.

Question 16

If a class in a frequency distribution has a frequency of zero, what does this indicate?

Accepted Answer

No data values fall within that class interval.

Question 17

Which of the following is the correct formula for the relative frequency of a class?

Accepted Answer

$$	ext{Relative Frequency} = \frac{	ext{Class Frequency}}{	ext{Sum of All Frequencies}}$$

Question 18

Why might you choose a more convenient value below the minimum data value as the first lower class limit?

Accepted Answer

To make the class intervals easier to interpret and use.

Exploring Data with Tables and Graphs: Frequency Distributions and Comparative Analysis

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