A population has size 7 at time t = 0, with t measured in years. (a) If the population grows by 15 people per year, find a formula for the population, P. at time t. P = help (formulas) (b) If the population grows by 15% per year, find a formula for the population, Q, at time t. Q= = help (formulas) (c) On a piece of paper, graph both functions on the same axes.