An entrepreneur is considering the purchase of a coin-operated laundr

1. An entrepreneur is considering the purchase of a coin-operated laundry. The current owner claims that over the past five years, the mean daily revenue was $675 with a population standard deviation of $75. A sample of 30 days reveals a daily mean revenue of $625. If you were to test the null hypothesis that the daily mean revenue was $675, which test would you use? 选项： A、Z test of a population mean B、Z test of a population proportion C、 t test of population mean D、t test of a population proportion

2.The marketing manager for an automobile manufacturer is interested in determining the proportion of new compact-car owners who would have purchased a side curtain air bag if it had been available for an additional cost of $300. The manager believes from previous information that the proportion is 0.30. Suppose that a survey of 200 new compact-car owners is selected and 79 indicate that they would have purchased the side curtain air bags. If you were to conduct a test to determine whether there is evidence that the proportion is different from 0.30, which test would you use? 选项： A、Z test of a population mean B、 Z test of a population proportion C、 t test of population mean D、 t test of a population proportion

3.To use a z statistic in a one-sample hypothesis test of a mean, we need to know:选项： A:the population mean.; B:the population standard deviation.; C:the degrees of freedom.; D:the margin of error.

4.A researcher is interested in testing to determine if the mean of population one is greater than the mean of population two. The null hypothesis is that there is no difference in the population means (i.e. the difference is zero). The alternative hypothesis is that there is a difference (i.e. the difference is not equal to zero). He randomly selects a sample of 9 items from population one resulting in a mean of 14.3 and a standard deviation of 3.4. He randomly selects a sample of 14 items from population two resulting in a mean of 11.8 and a standard deviation 2.9. He is using an alpha value of .10 to conduct this test. Assuming that the populations are normally distributed, the critical t-value from the table is _______.选项： A:1.323 B:1.721 C:1.717 D:1.321

5.A researcher is interested in testing to determine if the mean of population one is greater than the mean of population two. The null hypothesis is that there is no difference in the population means (i.e. the difference is zero). The alternative hypothesis is that there is a difference (i.e. the difference is not equal to zero). He randomly selects a sample of 9 items from population one resulting in a mean of 14.3 and a standard deviation of 3.4. He randomly selects a sample of 14 items from population two resulting in a mean of 11.8 and a standard deviation 2.9. He is using an alpha value of .10 to conduct this test. Assuming that the populations are normally distributed, the degrees of freedom for this problem are _______.选项： A:23 B:15 C:22 D:2

6.A researcher is interested in testing to determine if the mean of population one is greater than the mean of population two. The null hypothesis is that there is no difference in the population means (i.e. the difference is zero). The alternative hypothesis is that there is a difference (i.e. the difference is not equal to zero). He randomly selects a sample of 9 items from population one resulting in a mean of 14.3 and a standard deviation of 3.4. He randomly selects a sample of 14 items from population two resulting in a mean of 11.8 and a standard deviation 2.9. He is using an alpha value of .10 to conduct this test. Assuming that the populations are normally distributed, the degrees of freedom for this problem are _______.选项： A:15 B:22 C:2 D:23

7.The mean annual incomes of certified welders are normally distributed with the mean of $50,000 and a population standard deviation of $2,000. The ship building association wishes to find out whether their welders earn more or less than $50,000 annually. A sample of 100 welders is taken and the mean annual income of the sample is $50,350. If the level of significance is 0.10, what conclusion should be drawn? 选项： A:

Do not reject the null hypothesis as the test statistic is less than the critical value of t.

B:

Reject the null hypothesis as the test statistic is greater than the critical value of z.

C:

Do not reject the null hypothesis as the test statistic is less than the critical value of z.

D:

Reject the null hypothesis as the test statistic is greater than the critical value of t.

8.Using the confidence interval when conducting a two-tail test for the population mean we do not reject the null hypothesis if the hypothesised value for µ:

9.Which of the following statements are correct when deciding whether to use the z or the t distribution?选项： A:Use the z distribution in a test of proportions when nπ and n(1 - π) are greater than or equal to 5.; B:Use the z distribution when we have a normal population and we know the population standard deviation.; C:Use t when the population is normal and the population standard deviation is not known.; D:Use the t distribution in a test of proportions when nπ and n(1 - π) are greater than or equal to 5.

10.In finding a confidence interval for the population mean, the population standard deviation should be used if it is known. If the population standard deviation is not known, then it should be estimated with _______.选项： A:the sample variance B:the sample standard deviation C:the range D:the mean

11.Which of the following statements are correct when deciding whether to use the z or the t distribution?选项： A:Use the z distribution in a test of proportions when nπ and n(1 - π) are greater than or equal to 5.; B:Use the z distribution when we have a normal population and we know the population standard deviation.; C:Use t when the population is normal and the population standard deviation is not known.; D:All of the above statements are correct.

12.Which of the following would be an appropriate null hypothesis?选项： 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:Only A and C are appropriate.

13.Which of the following would be an appropriate null hypothesis? 选项： 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、Only (A) and (C) are true.

14.A manager of the credit department for an oil company would like to determine whether the mean monthly balance of credit card holders is equal to $75. An auditor selects a random sample of 100 accounts and finds that the mean owed is $83.40 with a sample standard deviation of $23.65. If you wanted to test whether the mean balance is different from $75 and decided to reject the null hypothesis, what conclusion could you reach?选项： A:There is not evidence that the mean balance is $75.; B: There is not evidence that the mean balance is not $75.; C:There is evidence that the mean balance is $75.; D:There is evidence that the mean balance is not $75.

15.A manager of the credit department for an oil company would like to determine whether the mean monthly balance of credit card holders is equal to $75. An auditor selects a random sample of 100 accounts and finds that the mean owed is $83.40 with a sample standard deviation of $23.65. If you wanted to test whether the mean balance is different from $75 and decided to reject the null hypothesis, what conclusion could you reach? 选项： A、There is not evidence that the mean balance is $75. B、 There is not evidence that the mean balance is not $75. C、There is evidence that the mean balance is $75. D、There is evidence that the mean balance is not $75.

16.Since a sample is a subset of the population, the sample mean（）.选项： A:is always smaller than the mean of the population; B:is always larger than the mean of the population; C:must be equal to the mean of the population; D:can be larger, smaller, or equal to the mean of the population

17.Which of the following would be an appropriate alternative hypothesis?选项： 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.

18.Suppose a population has a mean of 90 and a standard deviation of 28. If a random sample of size 49 is drawn from the population, the probability of drawing a sample with a mean of more than 95 is _______.

19.Consider an infinite population with a mean of 100 and a standard deviation of 20. A random sample of size 64 is taken from this population. The standard deviation of the sample mean equals 2.5.选项： A:对 B:错

20.We wish to develop a confidence interval for the population mean. The population follows the normal distribution, the standard deviation of the population is 3, and we have a sample of 10 observations. We decide to use the 90 percent level of confidence. The appropriate statistic for the level of confidence is:? z;= 1.960.z;= 1.645.t;= 2.262.t;= 1.833.