Question

If $8,000 is placed in an account with an annual interest rate of 4%, how long will it take the amount to quadruple if the interest is compounded annually? Round your answer to two decimal places

Answer 1

\[32000=8000(1+\frac{.04}{1})^{1(t)}\]

Answer 2

\[4=1.04^t\]
\[\ln 4=t \ln 1.04\]
\[t=\frac{\ln 4}{\ln 1.04}=35.3 years\]