Question

Find the doubling time of a quantity that is increasing 8% per year. Round your answer to two decimal places.

The doubling time is roughly _______ years.

Answer 1

I used:
P(t) = Poe^rt ---> P(t)=2Po ---> 2Po=Poe^rt

2=e^rt
ln(2)=rt
t=ln(2)/0.08 = 8.66 years

What did I do wrong?

Answer 2

Figured it out:
t = log 2/log 1.08 = 9.006468 years