# A sample of 81 observations from a normal population is taken with a

1. A sample of 81 observations from a normal population is taken with a standard deviation of 5. The sample mean is 40 Determine the confidence interval of 95% for the population mean.

2. MacBurger restaurant chain claims that the waiting time of customers is 3 minutes with a population standard distribution of 1 minute. The quality control department found a sample of 50 clients in Warren Road MacBurger that the average waiting time was 2.75 minutes. With the significance level of 0.05 can you conclude that the mean waiting time is less than 3 minutes?

3. Each month, the National Association of Purchasing Managers publishes the NAPM index. One of the questions posed in the survey of purchasing agents is: Do you think the economy is expanding? Last month, the 300 responses, 160 were affirmative. This month, 170 of the 290 responses indicated that the economy was expanding. With a significance level of 0.05. Can we conclude that a larger proportion of agents feel the economy is expanding this month?

4. A doctor who specializes in weight management recommends three different diets. As part of an experiment, 15 randomly selected patients and then assigns 5 of them to each diet. After three weeks the following weight reduction observed in pounds. With a significance level of 0.05 can you conclude that there is a difference in the average amount of weight loss among the three diets?

Plan A |
Plan B |
Plan C |

5 7 4 5 4 |
6 7 7 5 6 |
7 8 9 8 9 |

5. Which of the following statements are true with respect to the confidence intervals are correct?

a. Do not have negative numbers

b. Always based distribution with z

c. Must include the population parameter

d. None of the statements are correct

6. A confidence interval:

1. Always include the population parameter.

2. width decreases as the sample size increases.

3 None of the above.

4 can not include a value of 0.

7. We wish to develop a confidence interval for the population mean. The shape of the population is not known, but we have a sample of 40 observations. We decided to use the 92 percent level of confidence. The appropriate value of z is:

1- 1.75

2 -1.96

3 -2.58

4 -1.65

8. A point estimate is:

1- Always estimate the population mean.

2- Always equal to the value of the population

3- An estimate of the population parameter.

4- None of the above.

9. The alternative hypothesis:

1- Is accepted if the null hypothesis is rejected.

2- Always contain the equal sign.

3- Says the value of the sample mean.

4- None of the above.