
William W. answered 05/03/20
Math and science made easy - learn from a retired engineer
Population (P) as a function of time (t) in months for exponential growth would fit this general equation:
P(t) = P0(1 + r)t where R is thr growth rate in decimal form, and P0 is the initial population.
In this case P(t)/P0 = 3 when t = 6 so:
3 = (1 + r)6
31/6 = 1 + r
r = 31/6 - 1 = 0.200937
So, the equation becomes P(t) = P0(1.200937)t
To find when the population doubled, make P(t)/P0 = 2
2 = (1.200937)t
log(2) = log(1.200937)t
log(2) = t•log(1.200937)
t = log(2)/log(1.200937)
t = 3.79 months