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

$\frac{\text{Frequency of the class}}{\text{Total number of observations}}$

Question 1

Which statement about the sum of relative frequencies in a histogram is correct?

Accepted Answer

The sum of relative frequencies for all classes of a numerical variable is equal to 1.

Question 2

In constructing a frequency histogram, what does the height of each bar represent?

Accepted Answer

The number of observations in the class.

Question 3

Given a density histogram, what does the area of each bar represent?

Accepted Answer

The relative frequency of the class.

Question 4

A distribution of exam scores has one clear peak. How would you describe its modality?

Accepted Answer

Unimodal

Question 5

If the right tail of a unimodal distribution is longer than the left tail, how is the distribution described?

Accepted Answer

Skewed right

Question 6

Which of the following is the correct order for determining the four characteristics of a distribution with a numerical variable?

Accepted Answer

Identify outliers, determine the shape, measure and interpret the center, describe the spread.

Question 7

A relative frequency histogram is constructed for a set of test scores. If the largest relative frequency is $0.286$, which of the following is a suitable vertical axis scale?

Accepted Answer

$0.05, 0.10, 0.15, 0.20, 0.25, 0.30$

Question 8

Suppose the area of the bars in a density histogram for ticket prices at stadiums sums to $0.97$ for prices at least $20$. What is the proportion of stadiums with ticket prices less than $20$?

Accepted Answer

$0.03$

Question 9

Which diagram type is best for comparing the frequencies of classes for a single numerical variable?

Accepted Answer

Frequency histogram

Question 10

A model in statistics is best described as:

Accepted Answer

A mathematical description of an authentic situation.

Question 11

If a distribution is described as symmetric, which of the following must be true?

Accepted Answer

The left tail is roughly the mirror image of the right tail.

Question 12

Which of the following is NOT a benefit of using a frequency histogram?

Accepted Answer

Describe individual values for a small number of observations.

Question 13

A dataset of blood pressure readings is found to have two distinct peaks. How should its distribution be described?

Accepted Answer

Bimodal

Question 14

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

Accepted Answer

$\frac{	ext{Frequency of the class}}{	ext{Total number of observations}}$

Question 15

In a real-world scenario, a hospital wants to compare the proportion of patients in different age groups. Which graphical display is most appropriate?

Accepted Answer

Frequency bar graph

Question 16

Which step should be performed first when analyzing the distribution of a numerical variable?

Accepted Answer

Identify all outliers.

Question 17

A density histogram for the price of concert tickets shows the following areas for price ranges: $0.15$ for $20-29.99$, $0.25$ for $30-39.99$, and $0.10$ for $40-49.99$. What is the proportion of tickets priced at least $30$?

Accepted Answer

$0.25 + 0.10 = 0.35$; but also include $0.15$ for $20-29.99$ if 'at least $20$' is asked. For 'at least $30$', the answer is $0.25 + 0.10 = 0.35$.

Question 18

Which diagram type is best for finding the association between two numerical variables?

Accepted Answer

Time-series plot

Question 19

A distribution of household incomes is found to have more than two mounds. How is this distribution described?

Accepted Answer

Multimodal

Question 20

Which of the following is a correct statement about the total area of bars in a density histogram?

Accepted Answer

The total area of the bars is equal to 1.

Constructing Graphical and Tabular Displays of Data: Histograms and Distribution Shapes

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