Exponential Growth/Decay

Question

A logistic growth model for world​ population, f(x), in​ billions, x years after 1968 is

f(x)=(12.57)/(1+4.11e^−0.026x). According to this​ model, when will the world population be 8 ​billion?

Answer 1

Either

(1) plug in values of x and narrow down the years as you get f(x) closer and closer to 8 (billion). 76 is the value.

1968+76 = 2044

(2) Solve for x using f(x) = 8. Same answer.