A person invests $9400 in an account at 5% interest compound annually. When will the value of the in

A person invests $9400 in an account at 5% interest compound annually. When will the value of the investment be $12,800.

Let's take it one year at a time:
Year 1: 9,400(1.05) = 9,870
Year 2: 9,870(1.05) = 10,363.50
Year 3: 10,363.50(1.05) = 10,881.68
Year 4: 10.881.68(1.05) = 11,425.76
Year 5: 11,425.76(1.05) = 11,997.05
Year 6: 11,997.05(1.05) = 12.596.90
Year 7: 12,596.90(1.05) = 13,226.74

So it take 7 years to cross the $12,800 amount.