Nick borrowed $600 for 3 months. The banker said that Nick must repay the loan at the rate of $200 per month plus interest. The bank was charging a rate of 2 percentage points above the prime interest rate. The prime interest rate is the rate charged to preferred customers of the bank. During the first month the prime interest rate was 4.75%, during the second month it was 5%, and during the third month it was 5.25%.

(a) Find the amount Nick paid the bank at the end of the first month, at the end of the second month, and at the end of the third month. 

(b) What was the total amount of interest Nick paid the bank?