In 2007, Rachel borrowed $800 from a bank; she has repaid $2,700 after three years. At what rate of compound interest did the bank lend money to Rachel? (Interest is compounded annually).
Hint: A = P (1 + r)^n
A – amount of money paid after n years
P – principal amount
r – interest rate
n – number of years

Question

In 2007, Rachel borrowed $800 from a bank; she has repaid $2,700 after three years. At what rate of compound interest did the bank lend money to Rachel? (Interest is compounded annually).
Hint: A = P (1 + r)^n
A – amount of money paid after n years
P – principal amount
r – interest rate
n – number of years

anonymous · Answer

solve 2700 = 800*(1 + r)^3 ... by manipulating to isolate r (as in rate) 

EDIT: for Kyle's sake ... A = 2700, and the answer is 50% per year {otherwise, his steps are correct)