The amount of money, a, accrued at the end of n years when a certain amount, p , is invested at a compound annual rate, r, is given by the equation a =p(1+r)n. when joseph invests $500 in an account that pays 9% interest compounded annually, what is joe's approximate balance after 7 years? question 9 options: a) $258.38 b) $3815.00 c) $914.02 d) $932.54