A random sample of 121 checking accounts at a bank showed an average daily balance of $280. The population standard deviation is known to be $60.
a. Is it necessary to know anything about the shape of the distribution of the account balances in order to make an interval estimate of the mean of all the account balances? Explain.
b. Find the standard error of the mean.
c. Give a point estimate of the population mean.
d. Construct a 95% confidence interval estimate for the population mean.
e. Interpret the confidence interval estimate that you constructed in part d.