1.The manager of a grocery store has taken a random sample of 196 customers. The average length of time it took these 196 customers to check out was 4 minutes. It is known that the standard deviation of the population of checkout times is 2 minutes. With a 0.90 probability, the sample mean will provide a margin of error of

a.

1.645.

b.

1.960.

c.

0.235.

d.

2.757.

e.

2.350.

f.

2.960.

2.A random sample of 200 employees of a local firm has been taken. A 95% confidence interval estimate for the mean output for all employees of the company is 1200 to 1500. Which of the following statements is valid?

a.95% of the sample of employees has a mean output between 1200 and 1500.

b.There is a probability of 95 percent that the mean output lies between 1200 and 1500.

c.If the sampling procedure were repeated many times, 1.96% of the resulting confidence intervals would contain the population mean output.

d.95% of the population of employees has a mean output between 1200 and 1500.

e.If the sampling procedure were repeated many times, 95% of the sample means would be between 1200 and 1500.

f.None of the above statements are correct.