Question

April wants to borrow $400 from her father and is willing to pay $11 in interest. Her father wants to charge an interest rate of 3 %. Howlong can April keep the money?

Answer 1

Given that

April borrowed $400 (which is the principal)

He is willing to pay back $11 interest (this is the simple interest)

The father want an interest rate of 3% (this is the rate)

Thus, we want to find time

Solution

Recall the simple interest (S.I) formula

$\text{S}I=\frac{PRT}{100}$

As explained above P =$400, R = 3%, T =?, S.I = 11

We put the parameters into the formula and we solve for T

$\begin{gathered} \text{S}I=\frac{PRT}{100} \\ 11=\frac{400\times3\times T}{100} \\ 11=4\times3\times T \\ 11=12T \\ \therefore\text{ T =}\frac{11}{12}years \end{gathered}$

Therefore, April can keep the money for 11 months or 11/12 years