The rate of change of the volume of a snowball that is melting is proportional to the surface area of the snowball. suppose the snowball is perfectly spherical. then the volume (in centimeters cubed) of a ball of radius r centimeters is 4/3 πr3. the surface area is 4πr2. set up the differential equation for how r is changing. then, suppose that at time t = 0 minutes, the radius is 10 centimeters. after 5 minutes, the radius is 8 centimeters. at what time t will the snowball be completely melted?