Question

I can figure all of the other compound interest problems except these-In how many years would Ben's $100,000 take to be worth $250.000 if compounded annually at the rate of 6.5%?-Thanks and good night :)

Answer 1

250000 = 100000(1.065)^n , where n is the number of years
2.5 = 1.065^n
now you require to take logarithms of both sides
log 2.5 = log 1.065^n
log 2.5 = n(log 1.065)
n = log 2.5 / log 1.065 = 14.55 years

so about 14 years and 6 months