Question 1

Which of the following is an example of data measured at the interval level?

Accepted Answer

The temperature in Celsius recorded each hour.

Question 2

A researcher wants to study the average commute time for employees at a large company. She randomly selects 5 departments and surveys all employees in those departments. Which sampling method is she using?

Accepted Answer

Cluster sampling

Question 3

Which of the following best describes continuous data?

Accepted Answer

The height of students measured in centimeters.

Question 4

Given the following frequency distribution, what is the class midpoint for the class 20–29?

Class: 10–19, 20–29, 30–39
Frequency: 5, 8, 7

Accepted Answer

25

Question 5

A frequency histogram is constructed for a set of exam scores. Which of the following is NOT a correct practice?

Accepted Answer

Leaving gaps between the bars.

Question 6

Given the following data: 2, 4, 6, 8, 10. What is the mean using the formula $$\bar{x} = \frac{\sum x}{n}$$?

Accepted Answer

$$\bar{x} = 6$$

Question 7

Which of the following distributions is most likely to be skewed right?

Accepted Answer

Income of residents in a large city.

Question 8

Given the data set: 3, 7, 7, 9, 12. What is the mode?

Accepted Answer

7

Question 9

If the standard deviation of a data set is $$s = 4$$, what is the variance?

Accepted Answer

$$16$$

Question 10

Given the data set: 5, 8, 12, 15, 20. Calculate the z-score for the value 12 using $$z = \frac{x - \bar{x}}{s}$$, where $$\bar{x} is $$the mean and $$s is $$the standard deviation.

Accepted Answer

$$z \approx 0.13$$

Question 11

A student scored a z-score of $$z = 2.5 on a $$standardized test. Which statement is most accurate?

Accepted Answer

The student's score is significantly high.

Question 12

If a data value is at the 80th percentile, what does this mean?

Accepted Answer

80% of the data values are less than or equal to this value.

Question 13

In a deck of 52 cards, what is the probability of drawing a heart or a king? Use the Addition Rule.

Accepted Answer

$$\frac{16}{52}$$

Question 14

A fair coin is tossed three times. What is the probability of getting at least one head?

Accepted Answer

$$\frac{7}{8}$$

Question 15

A medical test correctly identifies a disease 95% of the time. If two patients are tested independently, what is the probability both tests are correct?

Accepted Answer

$$0.9025$$

Question 16

Which sampling method is most likely to introduce bias?

Accepted Answer

Convenience sampling

Question 17

Given the frequency distribution below, what is the cumulative frequency for the class 30–39?

Class: 10–19, 20–29, 30–39
Frequency: 4, 6, 10

Accepted Answer

20

Question 18

If a distribution is bell-shaped, which measure of central tendency is most appropriate to describe its center?

Accepted Answer

Mean

Question 19

A student randomly selects every 10th person entering a library to survey. Which sampling method is this?

Accepted Answer

Systematic sampling

Question 20

Given the data set: 2, 4, 6, 8, 10. What is the range?

Accepted Answer

8

Introductory Statistics Exam 1 Study Guide

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