Q: If the minimum commute time is 0 minutes and the maximum is 104 minutes, and you want 7 classes, what is the formula for class width?

$$ \text{Class width} = \frac{\text{Maximum value} - \text{Minimum value}}{\text{Number of classes}} $$

Question 1

Which of the following best describes the purpose of a frequency distribution table?

Accepted Answer

To show how data are partitioned among several categories by listing the categories along with the number of data values in each.

Question 2

Given the frequency distribution for daily commute times in Los Angeles, what is the class width?

Accepted Answer

$$ 15  ($$difference between consecutive lower class limits)

Question 3

What is the cumulative frequency for the class '30–44 minutes' in the given table?

Accepted Answer

$$ 6 + 18 + 14 = 38 $$

Question 4

Which of the following best describes the shape of the distribution shown in the histogram of commute times?

Accepted Answer

Skewed to the right (positively skewed)

Question 5

What is the main difference between a histogram and a relative frequency histogram?

Accepted Answer

A histogram uses frequencies on the vertical axis, while a relative frequency histogram uses proportions or percentages.

Question 6

If you were to add all the frequencies in the table, what would the total number of data values be?

Accepted Answer

$$ 6 + 18 + 14 + 5 + 5 + 1 + 1 = 50 $$

Question 7

Which value represents the class midpoint for the class '30–44 minutes'?

Accepted Answer

$$ \frac{30 + 44}{2} = 37 $$

Question 8

What is the lower class boundary for the class '15–29 minutes'?

Accepted Answer

$$ 14.5 $$

Question 9

Which of the following statements is true about the histogram shown?

Accepted Answer

The histogram shows that most people have commute times between 0 and 29 minutes.

Question 10

If you wanted to construct a cumulative frequency distribution from the given table, what would be the cumulative frequency for the class '60–74 minutes'?

Accepted Answer

$$ 6 + 18 + 14 + 5 + 5 = 48 $$

Question 11

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

Accepted Answer

Calculate the mean and median of the data.

Question 12

Suppose you want to identify outliers in the commute time data. Which graphical method would be most helpful?

Accepted Answer

Histogram

Question 13

If the minimum commute time is 0 minutes and the maximum is 104 minutes, and you want 7 classes, what is the formula for class width?

Accepted Answer

$$ 	ext{Class width} = \frac{	ext{Maximum value} - 	ext{Minimum value}}{	ext{Number of classes}} $$

Question 14

Which of the following best describes a normal distribution when graphed as a histogram?

Accepted Answer

A bell-shaped curve that is symmetric about the center.

Question 15

If a distribution is described as 'skewed to the right,' what does this mean?

Accepted Answer

The distribution has a longer right tail.

Organizing Data Visually: Frequency Distributions and Histograms

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