The volume of a growing spherical cell is given below, where the radius is measured in micrometers (1 µm = 10-6m).

Question

V = 4/3pi r^3
(a) Find the average rate of change of V with respect to r when r changes from 2. Evaluate your answers numerically.
(i) 2 to 5 µm ? µm^2
(ii) 2 to 3 µm ? µm^2
(iii) 2 to 2.1 µm ? µm^2