Based on these data a 99 confidence interval for in days is

Based on these data, a 99% confidence interval for ?, in days, is

A.65.00 ? 4.07.

B65.00 ? 1.55.

C.65.00 ? 3.09.

D.65.00 ? 2.35.

If we wanted the margin of error associated with this estimate to be 0.5 days, with a 99% confidence level, how many plants do we need to sample?

A.153 plants

B.143 plants

C.8 plants

D.163 plants

13. You plan to construct a confidence interval for the mean ? of a Normal population with (known) standard deviation ?. Which of the following will reduce the size of the margin of error?

A.Use a lower level of confidence.

B.Increase the sample size.

C.Reduce ?.

D.All answers are correct.

14. You plan to construct a 99% confidence interval for the mean ? of a Normal population with (known) standard deviation ?. By using a sample size of 400 rather than 100, you can reduce the margin of error by a factor of

A.2 (the new margin of error will be half that of the one based on 100 observations).

B.4 (the new margin of error will be 1/4 that of the one based on 100 observations).

C.16 (the new margin of error will be 1/16 that of the one based on 100 observations).

D.None of the answers is correct?it depends on the value of ?.

Solution

11) C) 65.00