Precalc question

Question

A ship embarked on a long voyage. At the start of the voyage, there were 500 ants in the cargo hold of the ship. One week into the voyage, there were 800 ants. Suppose the population of ants is an exponential function of time

(a) How long did it take the population to double?

(b) How long did it take the population to triple?

(c) When were there be 10,000 ants on board?

Answer 1

800 = 500e^r

8/5 = e^r

ln (8/5) = r

0.47 = r

(a) 2 = e^0.47t

(b) 3 = e^0.47t

(c) 10000/500 = e^0.47t