I am doing a self-study and review of calculus 1 material.

I came across this question.

Given p(t) = 500[1 + (4t/(50+t^2)]

Note that t is measured in hours.

Find the rate at which the population is growing

when t = 2.

Must I find the derivative of p(t) before replacing t with 2 or just plug t = 2 into the given formula?