Question

A person invested $200 in an account growing at a rate allowing the money to double every 13 years. How much money would be in the account after 15 years to the nearest dollar

Answer 1

Answer:

$431

Step-by-step explanation:

Given parameters:

Principal  = $200

Time given for the amount to double  = 13yrs

Unknown:

Amount in the account after 15yrs = ?

Solution:

To solve this problem, we need to find the interest rate on this investment.

    I = $\frac{PRT}{100}$

I = interest

P = principal

R = Rate

T = time

 Now,

  if the amount should double,

     Interest earned  = $200

So;

         200  = $\frac{200 x R x 13}{100}$  

         200  = 26 x R

           R = 7.7%

Now, in 15yrs, this amount will be;

 let us find the interest;

           I  = $\frac{200 x 7.7 x 15}{100}$  

           I = $231

The amount in the account will be:

  Amount  = Principal + Interest

  Amount = $200 + $231  = $431

Answer 2

Answer:

445

Step-by-step explanation:

y=a(2)t/d

​

a=200 d=13 t=15  d is the doubling time

y=200(2)15/13

y=445.012590439

y≈445