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 34 client audit fees. The sample mean audit cost was $710 with a standard deviation of $65. Complete parts a and b below.

Develop a 90% confidence interval estimate for the mean audit cost.