Question

Oliver's grandfather invested $150 at 5% interest compounded quarterly. When Oliver inherited it, the amount was $6000. For how many years had the $150 been invested?

Answer 1

0.05/4=1.25% quarterly interest
6000=150(1+0.0125)^n , n= number of quarters
(1+0.0125)^n=6000/150=40
n log (1.0125)=log 40
n=296.95 quarters
number of years=n/4=74.23 years.