8. Exercise Problem V

A vessel is in the form of an inverted cone. Its height is $8 cm$ and the radius of its top, which is open, is $5 cm$. It is filled with water up to the brim. When lead shots, each of which is a sphere of radius $0.5 cm$ are dropped into the vessel, one-fourth of the water flows out. Find the number of lead shots dropped in the vessel.

 

Number of sphere $=$