Answer
We need to invest the amount for 3 years.
Work Step by Step
The interest formula is: i = P $\times$ r $\times$ t.
To find the time needed to invest, or t, we divide i by P $\times$ r.
So, t = $\frac{i}{P\ \times\ r}$
P = 4000
i = 540
r = 4.5% = 0.045
Substitute these values into the formula to obtain the time needed to invest.
t = $\frac{540}{4000\times0.045}$
t = $\frac{540}{180}$
t = 3
We need to invest the amount for 3 years.
