Question

The simple interest formula I=prt gives the interest earned on an investment of p dollars at interest rate r for a time of t years. How much does Tanya need to invest at a rate of 8% in order to earn $800 interest in 5 years?

Answer 1

How much does she need to invest ? That would mean you are solving for principal.
I = PRT
I = 800
R = 8% = .08
T = 5
now sub your info into the formula and find P.
I = PRT
800 = P(.08)(5)
800 = p(0.4) -- now divide by 0.4
800/0.4 = p
2000 = p
check....
I = PRT
800 = (2000)(.08)(5)
800 = 800 (correct)

Tanya needs to invest $ 2000

any questions ?

Answer 2

Thank you! :)

Answer 3

anytime :)