Question 3 A spherical balloon with radius r inches has a volume V(r) = 4 3 πr3. (a) Find an expression for the amount of air required to inflate the balloon so that the radius increases from r to r+3. (b) Find an expression for the amount of air required to double the radius of the balloon from a radius of r to a radius of 2r. (c) If the balloon starts with a volume of 36π cubic inches and the radius is increasing at 1 inch per minute, then how long will it take for the balloon to inflate to a volume of 200 cubic inches?