1. Nationwide, the average waiting time until a electric utility customer service representative answers a call is 300 seconds per call.  The Gigantic Kilowatt Energy Company took a sample of 35 calls and found that, on the average, they answered in 240 seconds per call with a standard deviation of $50.  Can the company claim that they are faster than the average utility?

A) No, because –0.20 falls in the critical region

B) Yes, because –7.10 falls in the critical region

C) No, because –1.20 falls in the critical region

D) Yes, because –0.20 falls in the critical region

2. If the observed value is 4, the expected value is 5, and the standard error is 4, then the test value used for the z test is equal to

A)  –1.00    B)  0.25    C)  –0.25    D)  1.00

3. The average speed of greyhound dogs is about 18.8 meters per second.  A particular greyhound breeder claims that her dogs are faster than the average greyhound. In a sample of 45 of her dogs, they ran, on the average, 19.2 meters per second with a standard deviation of $1.4.  Is her claim correct?

A) Yes, because 0.4 falls in the noncritical region

B) No, because 0.04 falls in the noncritical region

C) Yes, because 0.04 falls in the noncritical region

D) No, because 1.92 falls in the noncritical region

4. For the conjecture "The average age of students in this class is 20", the null hypothesis is:

A) The average age of students in this class is not 20

B) We do not reject the hypothesis that the average age of students in this class is 20

C) We reject the hypothesis that he average age of students in this class is 20

D) The average age of students in this class is 20

5. What is the p-value for a one-sided test of the data provided above?

A)  0.0036     B)  0.1327     C)  0.0853     D)  0.0951 

6. At a certain university, the average cost of books per student was $400 per student last semester.  In a sample of 40 students this semester, their average cost was $430 with a standard deviation of $80.  The Dean of Students believes that the costs are greater this semester.  What is the test value for this hypothesis?

A)  15.00    B)  2.37    C)  0.38    D)  0.75

7. A medical researcher is interested in whether patients' left arms or right arms are longer.  If 14 patients participate in this study (so that n left arms and n left arms are measured), how many degrees of freedom should the researcher use in her t-test critical value?

A)  26    B)  27    C)  14    D)  13

8. Many elementary school students in a school district currently have ear infections.  A random sample of children in two different schools found that 16 of 42 at one school and 21 of 36 at the other had this infection.  At the .05 level of significance, is there sufficient evidence to conclude that a difference exists between the proportion of students who have ear infections at one school and the other?

A) No, there is not sufficient information to reject the hypothesis that the proportions of students at the two schools who have ear infections are the same because the test value –1.78 is inside the acceptance region (-1.96,1.96).

B) Yes, there is sufficient information to reject the hypothesis that the proportions of students at the two schools who have ear infections are the same because the test value –2.34 is outside the acceptance region (-1.96,1.96).

C) Yes, there is sufficient information to reject the hypothesis that the proportions of students at the two schools who have ear infections are the same because the test value –8.76 is outside the acceptance region (-1.96,1.96).

D) Yes, there is sufficient information to reject the hypothesis that the proportions of students at the two schools who have ear infections are the same because the test value –15.73 is outside the acceptance region (-1.96,1.96).

9. In testing the equality of the two means below, what is the test statistic?  (Use the unequal variances formula)

Sample 1 Sample 2

Sample size 9 12

Sample mean 80 115

Sample variance 550 100

A)  –4.20    B)  –2.31    C)  –0.18    D)  –0.50

10. In testing the equality of the two means below, what is the test statistic?  (Use the equal variances formula)

Sample 1 Sample 2

Sample size 12 8

Sample mean 115 80

Sample variance 700 450

A)  0.28    B)  3.12    C)  2.36     D)  1.56

11. 66% of students at a university live on campus.  A random sample found that 20 of 40 male students and 40 of 50 of female students lived on campus.  At the .05 level of significance, is there sufficient evidence to conclude that a difference exists between the proportion of male students who live on campus and the proportion of female students who live on campus?

A) No, there is not sufficient information to reject the hypothesis that the proportion of male students who live on campus and the proportion of female students who live on campus are the same because the test value –1.65 is inside the acceptance region (-1.96,1.96).

B) Yes, there is sufficient information to reject the hypothesis that the proportion of male students who live on campus and the proportion of female students who live on campus are the same because the test value –3.15 is outside the acceptance region (-1.96,1.96).

C) Yes, there is sufficient information to reject the hypothesis that the proportion of male students who live on campus and the proportion of female students who live on campus are the same because the test value –3.00 is outside the acceptance region (-1.96,1.96).

D) No, there is not sufficient information to reject the hypothesis that the proportion of male students who live on campus and the proportion of female students who live on campus are the same because the test value –0.30 is inside the acceptance region (-1.96,1.96).

12. In comparing the two variances below, what is the test value and what are the degrees of freedom that should be used?

Variance Number of values

Sample 1 6 18

Sample 2 11 29

A) test value = 1.83, degrees of freedom = 18 and 29

B) test value = 1.83, degrees of freedom = 17 and 28

C) test value = 0.55, degrees of freedom = 18 and 29

D) test value = 0.55, degrees of freedom = 17 and 28

13. A study of cats and dogs found that 11 of 50 cats and 21 of 50 dogs slept more than 10 hours per day.  At the .05 level of significance, is there sufficient evidence to conclude that a difference exists between the proportion of cats and the proportion of dogs that sleep more than 10 hours per day?

A) No, there is not sufficient information to reject the hypothesis that the proportion of cats and the proportion of dogs that sleep more than 10 hours per day are the same because the test value –0.65 is inside the acceptance region (-1.96,1.96).

B) Yes, there is sufficient information to reject the hypothesis that the proportion of cats and the proportion of dogs that sleep more than 10 hours per day are the same because the test value –2.14 is outside the acceptance region (-1.96,1.96).

C) No, there is not sufficient information to reject the hypothesis that the proportion of cats and the proportion of dogs that sleep more than 10 hours per day are the same because the test value –1.40 is inside the acceptance region (-1.96,1.96).

D) Yes, there is sufficient information to reject the hypothesis that the proportion of cats and the proportion of dogs that sleep more than 10 hours per day are the same because the test value –2.47 is outside the acceptance region (-1.96,1.96).

14. The possible relationship between pairs of data values could be examined from a

A) Histogram

B) Scatter plot

C) Pareto graph

D) Pie chart

15. Compute the standard error of the estimate for the data below.

X values –3 –2 2 5 10

Y values 4 6 –2 0 –3

A)  2.36    B)  1.96    C)  0.87    D)  1.35

16. Compute the slope of the regression line for the data below.

X values –3 0 3 5 10

Y values 7 4 –2 2 –3

A)  –4.13    B)  –0.72    C)  –1.70    D)  1.20

17. If the equation for the regression line is y = –4x + 7, then the slope of this line is

A)  –4    B)  3    C)  14    D)  7

18. Compute the correlation coefficient for the data below

X values –4 –1 1 3 4

Y values 3 –1 –2 3 1

A)  0.202    B)  0.013    C)  0.286    D)  –0.082

19. Compute the correlation coefficient for the data below

X values -2 -1 0 3

Y values 4 2 8 1

A)  –0.233    B)  0.000    C)  –0.349    D)  –57.500

20. Compute the correlation coefficient for the data below

X values –3 1 2

Y values 4 6 –2

A)  –0.227    B)  0.431    C)  –0.454    D)  –0.159