Problem $3$

Honest Joe$$s Used RVs offers the following payment options for a used $2015$ Freedom $314$SO:

$1.$ $$49,900$ in cash today;

$2.$ $$20,000$ down payment right now and then $$1,200$ monthly for the next three years $($i$.$e$.,36$ payments of $$1,200$

with the first payment due one month from today$).$

What effective monthly interest rate is he charging in the second payment option? Note: You can use the IRR

function or Goal Seek $($or Solver$)$ in Excel to solve this problem.