Question

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?

Answer 1

`\color(indianred)(8\text( years))`

Explanation:

Apply formula `I=Prt`
`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=(5000)(0.03)(t)`
The question wants you to find `t`.

Isolating said variable (you may need to use a calculator):
`1200/(5000\times0.03)=t, t=8`

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