1)What is the value of alpha for a 95% confidence interval to estimate the population mean?

:

2)What is the critical-valueZ_/2for an 85% confidence interval (use the Z-score chart).

Z_/2:

3)Find the critical-valuet_/2used to construct a 99% confidence interval for the mean with a sample size n=17(use the t-score chart).

4)In a random sample of 400 headache suffers, 85 prefer a particular brand of pain killer. Construct a 95% confidence interval for the true proportion of people with headaches who prefer this particular brand of pain killer. Round your answer to two decimals.

( P )

5)In a random sample of 400 headache suffers, 85 prefer a particular brand of pain killer. How large a sample is required if we want to be 99% confidence that our estimate of percentage of people with headaches who prefer this particular brand of pain killer is within2 percentage points? Round your answer to the next whole number.

n:

6)The weights of 10 randomly selected new born babies at a local hospital are:

6.55.87.27.08.26.26.77.58.57.8

Construct a 90% confidence interval for the mean weight of new born baby.

( )

7)The starting salaries of college instructors have a SD of $ 2000. How large a sample is needed if we wish to be 96% confident that our mean will be within $500 of the true mean salary of college instructors? Round your answer to the next whole number.

n:

Help I am stuck on all this problems :(