The formula for the volume of a sphere is s = 4 3 πr3, where r (in feet) is the radius of the sphere. suppose a spherical snowball is melting in the sun. (a) suppose r = 1 (t + 1)2 − 1 15 , where t is time in minutes. use the chain rule, ds dt = ds dr · dr dt , to find the rate at which the snowball is melting. ds dt = (b) use the results from part (a) to find the rate (in ft3/min) at which the volume is changing at t = 1 min. (round your answer to four decimal places.) ft3/min