# If a couple invests $5000 in an account that that earns a 3% interest rate, how long will they need to invest it to earn$1200 in interest?

Nov 14, 2016

$\setminus \textcolor{\in \mathrm{di} a n red}{8 \setminus \textrm{y e a r s}}$

#### Explanation:

Apply formula $I = P r t$
$I$ is interest, $P$ is principal/original, $r$ is interest rate and $t$ is time.

Here, we have:
$I = 1200$
$P = 5000$
$r = 0.03$

$1200 = \left(5000\right) \left(0.03\right) \left(t\right)$
The question wants you to find $t$.

Isolating said variable (you may need to use a calculator):
$\frac{1200}{5000 \setminus \times 0.03} = t , t = 8$

\text(You need )\color(red)(8)\text( years to earn )\$1200\text( in interest.)