text: compound interest? i need help with this problem:   $2250 is deposited in an account that pays 6% annual interest, compounded quarterly. find the balance after ten years.  thanks in advance!! the formula for compound interest is, iirc: p(1 + r/t)^ty, where p = principle, r = interest rate, t = times per year interest is compounded, and y = years.  2250(1.015)^40 = $4081.54