Donald wanted to ensure that he had $$70,000$ for his child's university education. As soon as his child was born, he started saving $$1,200$ every $6$ months in an investment fund. If he achieved his investment target on his child's $21$st birthday, and he made no deposit on the child's $21$st birthday, calculate the following:

a$.$ The nominal interest rate for the investment, compounded quarterly.

$\%$

Round to two decimal places.

b$.$ Calculate the effective interest rate for this investment.

$\%$

Round to two decimal places.