Problem $4-68$ Calculating Interest Rates

A financial planning service offers a college savings program. The plan calls for you to

make six annual payments of $$16,500$ each, with the first payment occurring today

on your child's $12$th birthday. Beginning on your child's $18$th birthday, the plan will provide

$$28,000$ per year for four years. What return is this investment offering? $($Do not round

intermediate calculations and enter your answer as a percent rounded to $2$ decimal

places, e$.$g$.,32\mathrm{.}16.)$

Return