A population grows at a rate P'(t) = 400te where P(t) is the population after t months. a. Find a formula for the population size after t months, given that the population is 5000 att = 0. b. Use the answer from part a to find the size of the population after 3 months. a. Find a formula for the population size after t months, given that the population is 5000 at t = 0. P(t) = (Type an exact answer in terms of e.)