Mr. Madoff invests 1000 dollars in a fund that compounds annually at a constant interest rate. After three years, his investment has grown to 1225 dollars. What is the annual interest rate? (Round your answer to the nearest integer.)
Thanks!
1225 = 1000 (1 + r)^3 divide both sides by 1000
1.225 = (1 + r)^3 take the cube root of each side
∛ 1.225 = 1 + r subtract 1 from both sides
∛1.225 - 1 = r ≈ 0.07 = 7 %
+1452 
