Q: What percentage of the day did the café serve 30 or more customers per hour? (Use the previous question's data.)

$$\frac{9}{14} \times 100 \approx 64.3\%$$

Q: When constructing a frequency distribution, what is the formula for calculating the class midpoint?

$$\frac{\text{lower class limit} + \text{upper class limit}}{2}$$

Q: If you are given only the number of classes (e.g., 6) and the data minimum and maximum, what is the formula to calculate the class width?

$$\frac{\text{max} - \text{min}}{\text{number of classes}}$$

Question 1

Which of the following graphs is most appropriate for visualizing qualitative (categorical) data such as eye color or nationality?

Accepted Answer

Pie Chart

Question 2

A frequency distribution table shows the frequency of observations versus chosen intervals of numbers, also known as:

Accepted Answer

Classes

Question 3

Given the following class limits for a frequency distribution: 20–29, 30–39, 40–49, what is the class width?

Accepted Answer

$$30 - 20 = 10 ($$but should use lower limits: $$30 - 20 = 10)$$

Question 4

If a café serves 14 hours and the number of customers served per hour is: 15, 24, 30, 21, 27, 35, 32, 31, 38, 41, 26, 33, 36, 40. How many hours did the café serve 30 or more customers?

Accepted Answer

9 hours

Question 5

What percentage of the day did the café serve 30 or more customers per hour? (Use the previous question's data.)

Accepted Answer

$$\frac{9}{14} 	imes 100 \approx 64.3\%$$

Question 6

When constructing a frequency distribution, what is the formula for calculating the class midpoint?

Accepted Answer

$$\frac{	ext{lower class limit} + 	ext{upper class limit}}{2}$$

Question 7

A histogram is best used to display which type of data?

Accepted Answer

Quantitative data

Question 8

If a frequency distribution has class limits 5–15, 16–26, 27–37, 38–48, 49–59, 60–70, 71–81, what is the class width?

Accepted Answer

$$16 - 5 = 11$$

Question 9

Which of the following best describes a distribution that has a longer tail on the right side?

Accepted Answer

Skewed Right

Question 10

A stem-and-leaf plot is most similar to which other graphical representation?

Accepted Answer

Histogram

Question 11

If you are given only the number of classes (e.g., 6) and the data minimum and maximum, what is the formula to calculate the class width?

Accepted Answer

$$\frac{	ext{max} - 	ext{min}}{	ext{number of classes}}$$

Question 12

In a frequency distribution, what does a relative frequency represent?

Accepted Answer

The frequency divided by the total number of measurements

Question 13

A company’s sales data for 15 representatives is divided into 5 classes. If the minimum sale is $$819 and the maximum is 1223$$, what is the class width (rounded up)?

Accepted Answer

$$\frac{1223 - 819}{5} = 80.8$$, round up to $$81$$

Question 14

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

Accepted Answer

Calculate the mean of the data

Question 15

If a histogram shows bars of approximately equal height across all classes, the distribution is best described as:

Accepted Answer

Uniform

Question 16

Given the following overtime hours worked by 12 employees: 3, 8, 5, 12, 14, 7, 9, 15, 10, 13, 4, 6. If the lower class limit is 3 and the class width is 4, what is the upper class limit of the first class?

Accepted Answer

$$3 + 4 - 1 = 6$$

Question 17

When using a TI-84 calculator to create a histogram, which step is necessary to adjust the class boundaries and frequencies?

Accepted Answer

Adjust class widths in WINDOW

Question 18

If a frequency histogram for books read in a month has classes 0–2, 3–5, 6–8, 9–11, 12–14, how many classes are there and what is the class width?

Accepted Answer

5 classes, class width is 3

Question 19

An economist is analyzing unemployment rates with a minimum of 16% and a maximum of 71%, divided into 7 classes. What is the class width (rounded up)?

Accepted Answer

$$\frac{71 - 16}{7} = 7.857$$, round up to $$8$$

Visualizing and Summarizing Data: Frequency Distributions and Histograms

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