Bob went on a diet. Bob's weight w in pounds t weeks after the start of the diet is modeled by w(t)=0.004r^3 + 0.18r^2 - 3t + 280 for 0≤ t ≤15
a) What was Bob's weight of the start of the diet
b) What was Bob's weight 15 weeks after the start of the diet (Show work)
c) Find and interpret the average rate of change of w over the interval [0,15] (show work)