Q: In a frequency distribution table, what is the formula for calculating the class width?

$$\text{Class Width} = \frac{\text{Highest Value} - \text{Lowest Value}}{\text{Number of Classes}}$$

Question 1

Which of the following best describes the difference between quantitative and qualitative data?

Accepted Answer

Quantitative data consists of numerical values that can be measured or counted, while qualitative data consists of descriptive labels or categories.

Question 2

A national survey asked 1261 US adults about their favorite fast-food meal (breakfast, lunch, dinner, snack). Which of the following is the implied population?

Accepted Answer

All US fast-food customers.

Question 3

Given the following frequency distribution for the number of gifts returned at a store:

$$\begin{array}{cc}
	ext{Number of Gifts Returned} & 	ext{Frequency} \
1 & 3 \
2 & 7 \
3 & 6 \
4 & 5 \
\end{array}$$

What is the relative frequency of returning 2 gifts?

Accepted Answer

$$\frac{7}{21} = 0.333$$

Question 4

A sample of pizza delivery times (in minutes) is: 3, 3, 8, 10. What is the sample mean?

Accepted Answer

$$\frac{3+3+8+10}{4} = 6$$

Question 5

Which measure of central tendency is most appropriate for describing the typical value in a highly skewed data set?

Accepted Answer

Median

Question 6

A box-and-whisker plot is constructed from the five-number summary. Which of the following is NOT part of the five-number summary?

Accepted Answer

Mean

Question 7

A class of students took a test. The scores were: 60, 70, 80, 90, 100. What is the sample variance?

Accepted Answer

$$\frac{(60-80)^2$ + (70-80)^2$ + (80-80)^2$ + (90-80)^2$ + (100-80)^2$}{5-1} = 250$$

Question 8

In a frequency distribution table, what is the formula for calculating the class width?

Accepted Answer

$$	ext{Class Width} = \frac{	ext{Highest Value} - 	ext{Lowest Value}}{	ext{Number of Classes}}$$

Question 9

A survey of 1000 students found that 240 are seniors, 80 are seniors who like vanilla ice cream, and 510 like vanilla overall. What is the probability that a randomly selected student is a senior who likes vanilla?

Accepted Answer

$$\frac{80}{1000} = 0.08$$

Question 10

Which of the following is a valid interpretation of probability in the context of a survey?

Accepted Answer

Probability is the ratio of the number of favorable outcomes to the total number of possible outcomes.

Question 11

A frequency distribution table for car mileages has the following classes: 10-12, 13-15, 16-18. What are the class boundaries for the first class?

Accepted Answer

$$9.5$$ and $$12.5$$

Question 12

If the median of a data set is 6, the mode is 3, and the mean is 8, which statement is most likely true about the distribution?

Accepted Answer

The distribution is skewed right.

Question 13

A sample of 5 delivery times (in minutes) is: 5, 7, 8, 9, 10. What is the interquartile range (IQR)?

Accepted Answer

$$Q_3$$ - $$Q_1 = 9 - 7 = 2$

Question 14

Which of the following is NOT a step in constructing a histogram from raw data?

Accepted Answer

Calculate the mean and median of the data.

Question 15

A survey of 1000 students found 130 juniors like chocolate ice cream and 270 juniors like vanilla. What is the probability that a randomly selected junior likes vanilla?

Accepted Answer

Question 16

Which of the following best describes the mode of a data set?

Accepted Answer

The value that occurs most frequently in the data set.

Question 17

A sample of 6 test scores is: 70, 75, 80, 85, 90, 95. What is the range?

Accepted Answer

$$95 - 70 = 25$$

Question 18

Which of the following is a valid reason to use a box-and-whisker plot?

Accepted Answer

To visually display the spread and center of a data set, including outliers.

Question 19

If a frequency distribution table has 5 classes and the lowest value is 10, the highest value is 35, what is the class width?

Accepted Answer

$$\frac{35-10}{5} = 5$$

Statistics Exam 1 Review: Key Topics and Examples

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