A loan of $$11,100$ is to be amortized with quarterly payments over $7$ years. If the interest on the loan is $16\%$ per year, paid on the unpaid balance, answer the following questions.

a$.$ What is the interest rate charged each quarter on the unpaid balance?

b$.$ How many payments are made to repay the loan?

c$.$ What payment is required quarterly to amortize the loan?

a$.$ The interest rate each quarter is $\%.$