1. Compounded continuously

Find out how long it takes a $3100 investment to double if it is invested at 7% compounded continuously. Round your answer to the nearest tenth of a year.$\displaystyle A=Pe^{rt}$I know I am looking for t in the formula. What do I do? 2. Step 1: Find out what you have$\displaystyle A = 6200 = 2(3100)\displaystyle P = 3100\displaystyle r = 7\% = .07\displaystyle t = ?$Step 2: Fill in what you know$\displaystyle A = Pe^{rt}\displaystyle 6200 = 3100e^{.07t}$Step 3: Solve for unknown$\displaystyle 6200 = 3100e^{.07t}\displaystyle 2 = e^{.07t}\displaystyle ln(2) = .07t\displaystyle \frac{ln(2)}{.07} = t\$

Put that in your calculator and you're done.