Question

After 4 years, Brian's account earned $1500 in interest. If the interest rate (in decimal form) is 0.1, how much did Brian initially invest?

Answer 1

Interest = Principal (initial investment) x Rate x Time

In this case, you know the interest earned ($1500), the interest rate (0.1 as a decimal), and the time (4 years). You want to find the principal (initial investment). Plug in the values:

$1500 = Principal x 0.1 x 4

Now, solve for the principal (initial investment):

$1500 = 0.4 * Principal

To isolate the Principal, divide both sides by 0.4:

Principal = $1500 / 0.4

Principal = $3750

So, Brian initially invested $3750.

Explanation: