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Quiz 3 - Chapter 9

Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.

1.

A Type II error is committed when
 a. a true alternative hypothesis is mistakenly rejected b. a true null hypothesis is mistakenly rejected c. the sample size has been too small d. not enough information has been available

2.

The level of significance in hypothesis testing is the probability of
 a. accepting a true null hypothesis b. accepting a false null hypothesis c. rejecting a true null hypothesis d. None of these alternatives is correct.

3.

In hypothesis testing if the null hypothesis has been rejected when the alternative hypothesis has been true,
 a. a Type I error has been committed b. a Type II error has been committed c. either a Type I or Type II error has been committed d. the correct decision has been made

4.

The probability of making a Type I error is denoted by
 a. a b. b c. 1 - a d. 1 - b

5.

Which of the following does not need to be known in order to compute the p-value?
 a. knowledge of whether the test is one-tailed or two-tailed b. the value of the test statistic c. the level of significance d. None of these alternatives is correct.

6.

A student believes that the average grade on the final examination in statistics is at least 85. She plans on taking a sample to test her belief. The correct set of hypotheses is
 a. H0: m < 85               Ha: m ³ 85 b. H0: m £ 85               Ha: m > 85 c. H0: m ³ 85               Ha: m < 85 d. H0: m > 85               Ha: m £ 85

Exhibit 9-7
A random sample of 16 statistics examinations from a large population was taken. The average score in the sample was 78.6 with a variance of 64. We are interested in determining whether the average grade of the population is significantly more than 75. Assume the distribution of the population of grades is normal.

7.

Refer to Exhibit 9-7. At 95% confidence, it can be concluded that the average grade of the population
 a. is not significantly greater than 75 b. is significantly greater than 75 c. is not significantly greater than 78.6 d. is significantly greater than 78.6

Exhibit 9-4
The manager of a grocery store has taken a random sample of 100 customers. The average length of time it took the customers in the sample to check out was 3.1 minutes with a standard deviation of 0.5 minutes. We want to test to determine whether or not the mean waiting time of all customers is significantly more than 3 minutes.

8.

Refer to Exhibit 9-4. The standardized test statistic is
 a. 1.96 b. 1.64 c. 2.00 d. 0.056

9.

Refer to Exhibit 9-4. The p-value is
 a. 0.025 b. 0.0456 c. 0.05 d. 0.0228

10.

Refer to Exhibit 9-4. At 95% confidence, it can be concluded that the mean of the population is
 a. significantly greater than 3 b. not significantly greater than 3 c. significantly less than 3 d. significantly greater then 3.18