The population of people is P(t) = 2.0 x 106 + 2.0 x 104t, and the mass per person W(t) (in kg) is W(t) = 80 - 0.5t.
The total mass of a population (in kg) as a function of the time, t, is the product of the number of individuals, P(t), and the mass per person, W(t) (in kg). In each of the above exercise, find the formula for the total mass, sketch graphs of P(t), W(t), and the total mass as functions of time for 0 ≤ t ≤ 100, and describe the results in words.