Zach borrowed 4,000 from his grandfather to buy a used car so he could travel to and from work. After working for 2 years, he has saved 5,200 to pay back to his grandfather. At what interest rate did Zach borrow the money? Round to the nearest whole percent.

Question

anonymous · Answer

Do you know the interest formula?

anonymous · Answer

no, that is were i go t stuck at on doing this problem.

anonymous · Answer

Google is your friend.
I assume compound interest

M = P( 1 + i )n
M is the final amount including the principal.
P is the principal amount.
i is the rate of interest per year.
n is the number of years invested.

Fill in the values

anonymous · Answer

sorry that should be $$M = P( 1 + i)^{n}$$