Question

Let f(x)=15/(1+4e^(-0.2x)
Over what interval is the growth rate of the function increasing?

(Please look at image for answer choices)

Answer 1

The interval of growth rate can be seen in the graph below


The answer is (-∞, ln(4)/0.2) =  (-∞, 6.9314)


(As x goes to infinity f(x) goes to 15)