Answer:
dh/dt = 0.0566 feet / min
Explanation:
Volume per second, dV/dt = 30 cubic feet per minute
Diameter of cone = height of cone = h
at h = 15 feet, dh/dt = ?
Volume of cone is
V = πr²h
where, r be the radius of cone
According to question
radius of cone = half of diameter of cone = h /2
So,


Differentiate both sides with respect to h

by substituting the values

dh/dt = 0.0566 feet / min