Question

Jennifer earned $249.60 in 6 1/2 years on a $640 investment. What was the simple interest rate?

Answer 1

I = P x R x T

$249.60 = $640 x R x 6 1/2

$249.60= 4160 x R

$249.60/4160 = 4160 /4160 x R

R= .06 * 100 = 6%

Check
I = P x R x T
$249.60 =$640 x 6% x 6 1/2
$249.60 = $249.60

Answer 2

R=i/pt
R=249.6/640*6.5
R=0.06*100=6%