Suppose you are in a hurry to get your income tax refund. If you mail your tax return, you will receive your refund in 3 weeks. If you file the return electronically through a tax service, you can get the estimated refund tomorrow. The service subtracts a $50 fee and pays you the remaining expected refund. The actual refund is then mailed to the preparation service. Assume you expect to get a refund of $978. What is the APR with weekly compounding? What is the EAR? How large does the refund have to be for the APR to be 15%?