An inverted right circular conical tank has a height of 10 ft and a base radius of 4 ft. Water is being pumped into the tank at a constant rate of 2 ft3/min. What is the rate at which the water depth h is rising when the depth is 5 ft?
a) 4π1 ft/min
b) 2π1 ft/min
c) −2π1 ft/min
d) 8π1 ft/min