You are shopping for a car and read the following advertisement in the newspaper.

"Own a new Spitfire! No money down. Four annual payments of just

$ 18 comma 000$18,000."

You have shopped around and know that you can buy a Spitfire for cash for

$ 57 comma 600.$57,600.

What is the interest rate the dealer is advertising (what is the internal rate of return

(IRR)

of the loan in the advertisement)? Assume that you must make the annual payments at the end of each year.