Mark invests $2,243 in a retirement account with a fixed annual interest rate of 3% compounded continuously. What will the account balance be after 15 years?

You start by multiplying 2,243 times 0.03 (The representation of 3% as a decimal)

After you get 67.29, you multiply that by 15.

So the answer is $1009.35 in interest rate in 15 years