Question

B(t)=4*e^0.8t, How many hours will it take for the population to grow to 400?

Answer 1

Given:  "B(t)=4*e^0.8t, How many hours will it take for the population to grow to 400?"   Set B(t) = 400.  Then:

400=4*e^(0.8t), or

100 = e^(0.8t)

Take the natural log of both sides, obtaining
                                       ln 100
ln 100 = 0.8t.  Then t = ----------- = 5.76 hours.
                                        0.8