Question

A person invested $\$1800$ in an account growing at a rate allowing the money to double every $8$ years.

How much money would be in the account after $12$years, to the nearest dollar?

Answer 1

Find the total amount in the account after $12$ years:

The total principal amount in the account is :

$P=\$1800$.

It is given that after $8$ years amount become double.

Now it is known that the formula to find the amount after any number of years when the time period for double the amount is given, is as follows:

$A=P{\left(2\right)}^{t/d}$, where $t$ is time for after we have to find the total amount and $d$ is the time taken by money to become double.

So here $P=1800,t=12,d=8$.

By applying these values :

$\begin{array}{rcl}A& =& 1800{\left(2\right)}^{\frac{12}{8}}\\ & \Rightarrow & A\approx 5091\end{array}$

Therefore, the total amount after $\mathbf{12}$ years in the account is $\mathbf{\$}\mathbf{5091}$.