AP Statistics

• The slope decreased and the r² increased.
• The slope increased and the r² decreased.
• The slope decreased but r² remained the same.
• Both slope and r² remained the same.

• A
• B
• C
• D

• B
• C
• D
• E

Which of the following statements about residuals are true?

• I and II

• I and III

• II and III

• I, II, and III

• None are true.

Answer explanation

• -0.64

• -0.80

• 0.64

• 0.80

• There is insufficient information to answer this question.

Answer explanation

We are given r-squared = 0.64.

To find r, we square root 0.64 AND give it the same sign as the slope. So, r = -0.80

A simple random sample of 25 world-ranked tennis players provides the following statistics: Number of hours practiced per day: mean = 7.3, standard deviation = 1.2 Yearly winnings: mean = $1,820,000, standard deviation = $310,000 Correlation = 0.23 Based on this data, what is the LSRL that predicts winnings from number of hours practiced?

• 0.28

• 0.45

• 0.56

• 0.90

• -0.28

Answer explanation

Correlation is unitless, so changing the values by shifting or rescaling or even switching x and y will not change the value of the correlation.

Which of the following are true statements about the correlation coefficient?

• I and II

• I and III

• II and III

• I, II, and III

• I or II

Answer explanation

Correlation is unitless, so changing measurements or changing which variable is x and which is y will not change correlation.

Correlation is greatly affected by outliers.

Which of the following statements about the correlation (r) are true?

• I only

• II only

• III only

• I, II, and III

• All are false.

Answer explanation

None of the statements are true.

I. r = 0 means there's no linear relationship, not no relationship.

II. r is never measured as a percent.

III. correlation doesn't prove causation.

A study is conducted relating AP Statistics exam scores to the total number of study hours for the AP Statistics class put in by students during the academic year, and the correlation is found to be 0.6. Which of the following are true statements?

• III only

• I and II

• I and III

• II and III

• I, II, and III