# Confidence Intervals and Hypothesis Test

The mean and standard deviation of the sample of 65 customer satisfaction ratings are x-bar = 42.95 and s = 2.6424. If we let "mu" denote the mean of all possible customer satisfaction ratings:

a) Calculate 95 and 99 percent confidence intervals for "mu".

b) Using the 95 percent confidence interval, can we be 95% confident that "mu" is greater than 42? Explain>

Suppose we wish to test H0: p = .8 versus Ha: p > .8 and that a random sample of n = 400 gives a

sample proportion = .86.

a Test H0 versus Ha at the .05 level of significance by using a rejection point. What do you conclude?

b Find the p-value for this test.

c Use the p-value to test H0 versus Ha by setting alpha equal to .10, .05, .01, and .001. What do you

conclude at each value of alpha?

#### Solution Summary

In this solution, formulas, calculation details and explanations are provided for two problems. The first problem finds 95 and 99 percent confidence intervals for a mean. The second problem conducts a hypothesis test for a mean.