# compute the value of the correlation coefficient

1. Compute the value of the correlation coefficient.

x 49 60 42 55 52

y 305 330 255 308 285

A) 0.912

B) 0.945

C) 0.892

D) 0.707

2. If the equation for the regression line is y’ = 11x + 8, then a value of x = –1 will result in a predicted value for y of

A) 8

B) 3

C) –3

D) 11

3. If the correlation coefficient is 0.790, what is the explained variation?

A) 37.6%

B) 62.4%

C) 79%

D) 21%

4. If the correlation coefficient is 0.930, what is the unexplained variation?

A) 7%

B) 93%

C) 13.5%

D) 86.5%

5. The total blood cholesterol concentrations, in mg/dL, are shown below for a random sample of six people. In the table below, x is the age of the subject and y is the subject’s total cholesterol concentration. Find the 95% prediction interval when x = 53 years.

x (age) 36 43 53 67 66 78

y (mg/dL) 208 224 238 238 277 263

6. A psychologist wants to determine if there is a linear relationship between the number of hours a person goes without sleep and the number of mistakes he/she makes on a simple test. The following data is recorded. Determine the regression line equation

Hours without Sleep, x 32 38 48 24 46 35 30 34 42

Number of Mistakes, y 6 8 13 5 7 6 5 8 12

7. An anatomy teacher hypothesizes that the final grades in her class are distributed as 10% A’s, 23% B’s, 45% C’s, 14% D’s, and 8% F’s. At the end of the semester, she has the following grades.

A B C D F

6 14 22 8 4

Find the critical value. Use alpha= 0.05

A) 9.236

B) 7.779

C) 11.070

D) 9.488

8. ANOVA is an abbreviation for the following term:

A) analysis of variance

B) variance

C) Scheffé test

D) Tukey test

9. The head of the English department wants to determine if the average number of students taking an English course differs depending upon the time of day that the course is being offered. Is there a significant difference between the mean attendance for the classes given for 0.05 alpha ?

Morning 25 26 27 26 27

Afternoon 25 24 18 20 23

Evening 27 26 24 23 25

A) Yes, there is a significant difference between the means.

B) No, there is no significant difference between the means.

C) The F-test cannot be used to answer whether or not there is a significant difference between the means.

10. A contingency table has 5 rows and 4 columns. How many degrees of freedom are there?

A) 20

B) 12

C) 16

D) 15