Example-18.How many spherical balls can be made out of a solid cube of lead whose edge measures 44 cm and each ball being 4 cm. in diameter.

Solution : Side of lead cube = 44 cm.

Radiusofsphericalball= 4/2 cm. =2cm.

Now volume of a spherical ball = 4/3 pr 3

= 4 ́22 ́23 cm3 37 = 4 ́ 22 ́8 cm3 37 Let the number of balls be ‘x’.

Volumeof x sphericalball = 4 ́ 22 ́8 ́x cm3 37

It is clear that volume of x spherical balls = Volume of lead cube




Hence, total number of spherical balls = 2541.

Example-19.A women self help group (DWACRA) is supplied a rectangular solid (cuboid shape) of wax block with dimensions 66 cm, 42 cm, 21 cm, to prepare cylindrical candles each 4.2 cm in diameter and 2.8 cm of height. Find the number of candles prepared using this solid.

Solution : Volume of wax in the rectangular solid = lbh =(66 ́42 ́21)cm3.

Radius of cylindrical candle = 4.2cm.=2.1cm. 2 Height of cylindrical candle =2.8cm.