so so confused. had to miss a week of class. any guidance is greatly appreciated.

a random sample of 121 checing accounts at a bank showed an average daily balance of $280. the standard deviation of the population is known to be $66

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) determine the margin of error for a 95% confidence interval

e) construct a 95% confidence interval for the mean