Question 1

A researcher collects data on the heights (in centimeters) of 50 adult men. What is the observational unit and what type of variable is height?

Accepted Answer

The observational unit is 'adult men'; height is a quantitative continuous variable.

Question 2

Which of the following graphs would be most appropriate for displaying the distribution of a categorical variable such as favorite ice cream flavor among 200 students?

Accepted Answer

Bar graph

Question 3

A data set of exam scores is summarized as follows: min = 45, Q1 = 60, median = 70, Q3 = 80, max = 100. What is the interquartile range (IQR)?

Accepted Answer

$$IQR = Q3 - Q1 = 80 - 60 = 20$$

Question 4

A distribution of household incomes is strongly skewed to the right. Which measure of center and spread is most appropriate to describe this distribution?

Accepted Answer

Median and interquartile range (IQR)

Question 5

A set of data has a mean of 50 and a standard deviation of 5. If every value in the data set is increased by 10, what will be the new mean and standard deviation?

Accepted Answer

Mean = 60, standard deviation = 5

Question 6

Which of the following statements about standard deviation is TRUE?

Accepted Answer

Standard deviation is not resistant to outliers.

Question 7

A student scored 85 on a test where the mean was 80 and the standard deviation was 2.5. What is the student's z-score?

Accepted Answer

$$z = \frac{85 - 80}{2.5} = 2$$

Question 8

In a normal distribution, approximately what percentage of data falls within two standard deviations of the mean?

Accepted Answer

95%

Question 9

A cumulative relative frequency graph shows that 70% of students scored less than or equal to 75 on a test. What is the percentile of a student who scored 75?

Accepted Answer

70th percentile

Question 10

Which of the following is NOT a property of the standard deviation?

Accepted Answer

It is resistant to outliers.

Question 11

A histogram of exam scores is approximately symmetric and mound-shaped. Which of the following is most likely TRUE?

Accepted Answer

The mean and median are approximately equal.

Question 12

A data set has the following five-number summary: min = 10, Q1 = 20, median = 30, Q3 = 40, max = 100. According to the 1.5*IQR rule, which value is an outlier?

Accepted Answer

100

Question 13

If you multiply every value in a data set by 3, what happens to the mean and standard deviation?

Accepted Answer

Both the mean and standard deviation are multiplied by 3.

Question 14

A boxplot is drawn for the weights of two different dog breeds. Breed A's boxplot is much wider than Breed B's. What does this indicate?

Accepted Answer

Breed A has greater variability in weights than Breed B.

Question 15

Which of the following best describes a variable that can only take the values 0 or 1?

Accepted Answer

Binary categorical variable

Question 16

A hospital records the blood types of 500 patients. Which of the following is the best way to display this data?

Accepted Answer

Bar graph

Question 17

A stemplot of ages in a retirement community shows two distinct peaks, one around 65 and another around 80. How would you describe the shape of this distribution?

Accepted Answer

Bimodal

Question 18

A normal probability plot for a data set is approximately linear. What does this suggest about the data?

Accepted Answer

The data is approximately normally distributed.

Question 19

A student’s test score is at the 90th percentile. How should this be interpreted?

Accepted Answer

The student scored as well as or better than 90% of the students.

Question 20

A data set of daily temperatures (in °F) is transformed to Celsius using the formula $$C = \frac{5}{9}(F - 32). $$How does this transformation affect the standard deviation?

Accepted Answer

The standard deviation is multiplied by $$\frac{5}{9}.$$

Statistics Unit I Test Study Guide: Data, Distributions, and Descriptive Statistics

Guida di studio - Domande di pratica

Study guide - Flashcard