Carlos purchased a machine for $$25,500$ for her company. She paid $5\mathrm{.}00\%$ of this amount as a down payment and financed the rest at $6\mathrm{.}52\%$ compounded quarterly. She paid $$1,125$ at the end of every quarter to settle the loan.

a$.$ What was the principal portion of payment number $4?$

Round to the nearest cent

b$.$ What was the interest portion of payment number $4?$