Some accounting firms give the client an option to pay a fee when the tax return is completed that guarantees

Some accounting firms give the client an option to pay a fee when the tax return is completed that guarantees tax advices and support from the accountant if the client were audited. A large accounting firm is trying to determine what fee to charge for next​ year's returns. In previous​ years, the actual mean cost to the firm for attending a client audit session was ​$740. To determine if this cost has​ changed, the firm randomly samples 32 client audit fees. The sample mean audit cost was ​$690 with a standard deviation of ​$75
.  address the problems that follow. 

Develop a 99% confidence interval estimate for the mean audit cost and address other interpretations related to the confidence intervals.