Your roommate has a great business idea, but needs a little more money to get it off the ground. You offer your entire savings of $15,480 as a silent partner in his business. You think that over the first 7 years, the value of your investment will grow to be worth $54,237. What annual rate of return does that represent? Please enter your answer without the "\%" sign (in other words as 12.45 for 12.45\%)