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 ?$650. To determine if this cost has?changed, the firm randomly samples 35 client audit fees. The sample mean audit cost was ?$670 with a standard deviation of ?$65. Complete parts a and b below.

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