Please hurry! help me solve this word problem that involves compounded continuously and doubling

Question

If an account pays 3.5% interest compounded continuously, how long it will take for an investment to double? (Round your answer to the whole number).

Hint. You can choose the amount of the investment.

Answer 1

f(t) = pe^rt, where p = principal, e = Euler's constant, r = rate, t = time

 

2 = e^0.035(t)

ln 2 = ln e^0.035(t)

ln 2 = 0.035t ln e

0.693 ≈0.035t 

19.8 ≈ t