An initial investment of 9000 grows at an annual interest ra

An initial investment of $9000 grows at an annual interest rate of 5% compounded continuously.  How long will it take to double the investment?

1 year

14.40 years

13.86 years

14.86 years

13.40 years

Solution

Amount = principale^(rate*time)

So, 18000 = 90000e^(0.05t)

2 = e^(0.05t)

take natural log on both sides:

ln2 = 0.05t

t = 13.86 years