For the car loan described, give the following information.

A newspaper advertisement offers a $$14,950$ car for nothing down and $48$ easy monthly payments of $$489\mathrm{.}40.$

$($a$)$ amount to be paid

$$8,589\mathrm{.}20x$

$($b$)$ amount of interest

$$8,589\mathrm{.}20,$ &

$($c$)$ interest rate $($Round your answer to two decimal places.$)$

$\%$

$($d$)$ APR $($rounded to the nearest tenth percent$)$