
AGE 
GPA 

AGE 
Pearson Correlation: 
1.000 
.031 
GPA 
Pearson Correlation: 
.031 
1.000 
5. A researcher interested in what characteristics were correlated with student use of computerassisted lessons found a correlation of .4153 between the number of lessons a student took and the student's highschool gradepoint average.
6. We expect that as cars get older and have more miles, their value will decrease. We can check this expectation in a preliminary way with correlation. Taking a sample of Cadillacs listed for sale in the want ads of a large city paper, I fed their prices, ages, and mileage into a statistical computer program and got the following results:
PRICE 
MILES 
AGE 
YEAR 

PRICE 
Pearson Correlation: 
1.000 
.777 
.870 
870 
MILES 
Pearson Correlation: 
.777 
1.000 
.593 
.593 
AGE 
Pearson Correlation: 
.870 
.593 
1.000 
1.000 
YEAR 
Pearson Correlation: 
870 
.593 
1.000 
1.000 
7. Suppose we are interested in the correlation between last year's income and this year's income for a group of people.



A 
$26,000 
$26,000 
B 
$40,000 
$20,000 
C 
$12,000 
$36,000 
D 
$20,000 
$20,000 
E 
$14,000 
$27,000 
8. Otto Mobile collects data from 25 cars. He then computes a correlation between weight of the car and its gas mileage. The answer he arrives at is 1.4. Interpret.
9. Brandon Cumber takes 50 numbers from a table of random numbers. He calls the first 25 the X variables and the second 25 the Y variables and computes a correlation. Computing a tvalue from the formula t=(r0)/(standard error of p) he gets 2.102 with 23 degrees of freedom. He therefore claims that he has conclusively proven that either the procedure does not work as advertised or that the table of numbers is not random. Evaluate his claim.
10. Doyle Zirkle is certain that there is a relationship between the kind of clothes people wear and their personalities. He has heard that correlation is a way of measuring how strong relationships are so he asks you to help compute a correlation to prove that he is correct. Assuming you want to help him, what should you say or do?
11. There is a relationship between X and Y on the graph below. However, the correlation coefficient will be close to zero. Explain why and illustrate on the graph.