STAT 104 Quiz 7

13) What is the conclusion of the above hypothesis test? a. Reject the null b. Fail to reject the null

a. Reject the null

14) Woof Chow Dog Food Company believes that is has a market share of 25 percent. It surveys n=100 dog owners and ask whether or not Woof Chow is their regular brand of dog food, and 23 people say yet. Based upon this information, what is the value of the test statistic? a. -0.462 b. -0.475 c. 0.856 d. -0.637

a. -0.462

11) Which of the following would be an appropriate null hypothesis? a. The mean of a population is equal to 55 b. The mean of a sample is equal to 55 c. The mean of a population is greater than 55 d. The mean of a sample is greater than 55

a. The mean of a population is equal to 55

1) A type II error occurs when: a. The null hypothesis is incorrectly accepted when it is false b. The null hypothesis is incorrectly rejected when it is true c. The sample mean differs from the population mean d. The test is biased

a. The null hypothesis is incorrectly accepted when it is false

10) A major package delivery company claims that more than 95 percent of the packages it delivers reach the destination on time. As part of the evidence in a lawsuit against the package company, a random sample of n=200 packages was selected. A total of 188 of these packages were delivered on time, the test statistics for this test is approximately -0.65. a. True b. False

a. True

4) In hypothesis testing, the null hypothesis should contain the equality sign. a. True b. False

a. True

5) A sample is used to obtain a 95 percent confidence interval for the mean of a population. The confidence interval goes from 15 to 19. If the same sample had been used to test the null hypothesis that the mean of the population is equal to 20 versus the alternative hypothesis that the mean of the population differs from 20, the null hypothesis could be rejected at a level of significance of 0.05. a. True b. False

a. True

8) Lube-Tech is a major chain whose primary business is performing lube and oil changes for passenger vehicles. The national operations manager has stated in an industry newsletter that the mean number of miles between oil changes for all passenger cars exceeds 4,200 miles. To test this, an industry group has selected a random sample of 100 vehicles that have come into a lube shop and determined the number of miles since the last oil change and lube. The sample mean was 4,278 and the sample standard deviation was 780 miles. Based on this information, the test statistic is approximately t=1.000. a. True b. False

a. True

2) Of type I and type II error, which is traditionally regarded as more serious? a. Type I Error. b. Type II Error c. Both of them d. Neither of them is serious

a. Type I Error.

12) A concern of Major League Baseball is that games last too long. Some executives in the league's headquarters believe that the mean length of games this past year exceeded 3 hours (180 minutes). To test this, the league selected a random sample of 80 games and found the following results: sample mean=183 minutes and s=16 minutes. Based on these results, what is the p-value for testing: 𝐻": 𝜇 = 180 𝐻*: 𝜇 > 180 a. 0.0309 b. 0.0484 c. 0.05513 d. 0.0978

b. 0.0484

6) A conclusion to "not reject" the null hypothesis is the same as the decision to "accept" the null hypothesis. a. True b. False

b. False

7) The Adams Shoe Company believes that the mean size for men's shoes is now more than 10 inches. To test this, it has selected a random sample of n=100 men. Assuming that the test is to be conducted using a .05 significance, a p-value of .07 would lead the company to conclude that its belief is correct. a. True b. False

b. False

9) Lube-Tech is a major chain whose primary business is performing lube and oil changes for passenger vehicles. The national operations manager has stated in an industry newsletter that the mean number of miles between oil changes for all passenger cars exceeds 4,200 miles. To test this, an industry group has selected a random sample of 100 vehicles that have come into a lube shop and determined the number of miles since the last oil change and lube. The sample mean was 4,278 and the sample standard deviation was 780 miles. Based on this information, the p-value for the hypothesis test is less than 0.10. [feel free to use R] a. True b. False

b. False

3) The form of the alternative hypothesis can be: a. One-tailed b. Two-tailed c. Neither d. One or two-tailed

d. One or two-tailed