Question

Sara wants to invest $200 in an account that compounds interest monthly. She wants to have $1000 in 7 years. What should her interest rate be?

i know the equation is 1000=200(1+r/12)^84

how do you solve for r

Answer 1

5 = (1+r/12)^84
log 5 = 84log(1+r/12)
log (1+r/12) = log 5 x 1/84
= 0.699/84
1+r/12 = 10^(0.699/84)
= 1.02
r/12 = 0.02
r= 0.24