Question

James invested $4,000 in his college fund. Several years later he had earned $2,240 in interest at a simple interest rate of 8%. How long was James money invested in the college fund.

Answer 1

$\begin{gathered} \text{ Since he earned \ 2240 in interest, then the total amount was} \\ 6240\text{, now using the equation of simple interest,} \\ A=P(1+rt) \\ 6240=4000(1+0.08t) \\ \frac{6240}{4000}=1+0.08t \\ 1.56-1=0.08t \\ 0.56=0.08t \\ t=\frac{0.56}{0.08} \\ t=7 \\ \\ \\ \text{the answer is 7 years!} \end{gathered}$