whater drains from the conical tank at the rate of 5 ft^3/min.

the radius of the conical tank is 4' and the hight is 10'

the radius of the water in the tank is r and the hight is h...

a) what is the relationship between the variables h and r in the figure?

the answ for this one is r=(2/5)h .. but why?

B) how fast is the water level dropping when h=6ft??