8 Air is being pumped into a spherical balloon at the rate of 7 cm3 s-1. Find the rate of change of the balloon's radius, in terms of n, when the volume of air in the balloon is 367 cm3. 9 Water is poured into a conical tank at the rate of 3 m3 per minute. The tank stands with the point downward. Determine how fast the water level in the tank is rising when the depth is 2 m and the radius of the water surface is 1.5 m