4 Question 3 A spherical balloon with radius r inches has a volume V0") : gen3. (a) Find an expression for the amount of air required to inate the baliocm 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 21'. (c) If the balloon starts with a volume of 3611' cubic inches and the radius is increasing at 1 inch per minute, then how long will it take for the baiioon to inate to a volume of 200 cubic inches