Yumiko invests $4000 in a Certificate of Deposit at 8.2% interest compounded 3 times per year.

  1. Find the equation that represents the account balance at time LaTeX: \displaystyle t .
  2. When will the account double? e.g. when will it be $8000. Round your solution to the nearest tenth of a year.

  1. Using the compounded interest formula gives LaTeX: \displaystyle A = 4000 \cdot 1.02733333333333^{3 t} .
  2. It will take about 8.6 years.