Q: Given the following five-number summary for exam scores: minimum = 50, Q1 = 60, median = 70, Q3 = 80, maximum = 100. What is the interquartile range (IQR)?

$$\text{IQR} = Q_3$ - Q_1$ = 80 - 60 = 20$$

Q: A teacher calculates the weighted mean of grades where homework counts for 20%, quizzes for 30%, and exams for 50%. If a student scores 80 on homework, 70 on quizzes, and 90 on exams, what is the weighted mean?

$$0.2 \times 80 + 0.3 \times 70 + 0.5 \times 90 = 16 + 21 + 45 = 82$$

Question 1

Which of the following best describes the difference between an observational study and an experiment?

Accepted Answer

In an experiment, researchers actively assign treatments to subjects and measure the response, while in an observational study, they only observe subjects without intervention.

Question 2

A pharmaceutical company wants to test a new drug. They randomly assign patients to receive either the drug or a placebo, and neither the patients nor the doctors know which treatment is given. What type of experiment is this?

Accepted Answer

Double-blind experiment

Question 3

Which sampling method is most appropriate when a university wants to survey students from each year (freshman, sophomore, junior, senior) to ensure all groups are represented?

Accepted Answer

Stratified sample

Question 4

A data set contains the following values: 2, 4, 4, 6, 8. What is the mode of this data set?

Accepted Answer

4

Question 5

Which of the following is a measure of dispersion?

Accepted Answer

Standard deviation

Question 6

Given the following five-number summary for exam scores: minimum = 50, Q1 = 60, median = 70, Q3 = 80, maximum = 100. What is the interquartile range (IQR)?

Accepted Answer

$$	ext{IQR} = Q_3$ - Q_1$ = 80 - 60 = 20$$

Question 7

A student scored 85 on a test where the mean was 80 and the standard deviation was 5. What is the student's z-score?

Accepted Answer

$$z = \frac{85 - 80}{5} = 1$$

Question 8

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

Accepted Answer

Qualitative data are categorical, while quantitative data are numerical.

Question 9

A frequency polygon is used to:

Accepted Answer

Show the distribution of a quantitative variable using line segments connecting midpoints of class intervals

Question 10

If a histogram of exam scores is skewed to the right, which measure of central tendency is likely to be the largest?

Accepted Answer

Mean

Question 11

A misleading graphic might distort data by:

Accepted Answer

Using inconsistent scales on axes

Question 12

The Empirical Rule states that for a normal distribution, approximately what percentage of data falls within two standard deviations of the mean?

Accepted Answer

95%

Question 13

Chebyshev’s Inequality can be used to estimate the minimum proportion of data within $$k$$ standard deviations of the mean for any distribution. What is the formula?

Accepted Answer

$$1 - \frac{1}{k^2$}$$

Question 14

A teacher calculates the weighted mean of grades where homework counts for 20%, quizzes for 30%, and exams for 50%. If a student scores 80 on homework, 70 on quizzes, and 90 on exams, what is the weighted mean?

Accepted Answer

$$0.2 	imes 80 + 0.3 	imes 70 + 0.5 	imes 90 = 16 + 21 + 45 = 82$$

Question 15

Which of the following statements about correlation and causation is correct?

Accepted Answer

Correlation does not imply causation.

Question 16

Given the least squares regression line $$y = 2x + 5$$, what is the predicted value of $$y$$ when $$x = 3$$?

Accepted Answer

$$y = 2 	imes 3 + 5 = 11$$

Question 17

If the linear correlation coefficient $$r is $$close to 0, what does this indicate about the relationship between two variables?

Accepted Answer

There is little to no linear relationship.

Question 18

The coefficient of determination $$R^2 is $$interpreted as:

Accepted Answer

The proportion of variation in the response variable explained by the explanatory variable.

Question 19

A scatter diagram shows points clustered closely around a straight line. What does this suggest about the variables?

Accepted Answer

There is a strong linear relationship.

Introductory Statistics Exam 1 Study Guide: Chapters 1–4

Study Guide - Practice Questions

Study Guide - Flashcards