Question

You are borrowing $4,285 to purchase a computer using a 36 month installment plan. Determine the annual percentage rate (APR) and the monthly payment given that the interest charge is $513.26. Round your answer to the nearest whole percent and to the nearest cent. a. 8%; $134.27 c. 7%; $133.29 b. 8%; $150.36 d. 7%; $148.16

Answer 1

The total of principal and interest is

... $4285 +513.26 = $4798.26

Dividing this into 36 equal payments gives a payment amount of ...

... $4798.26/36 = $133.285

There is no formula that will give the interest rate as a function of payment, principal, and time, but the appropriate equation can be solved graphically or iteratively. The result is the interest rate for this payment value is about 7.497%.

These numbers are consistent with answer choice ...

... c. 7%; 133.29

_____

Of course, that answer can be selected simply on the basis of the payment value.

The interest rate corresponding to a payment of 133.29 is 7.4999264%, which still rounds down to 7%.