(Q9)A Women self help group (DWACRA) is supplied a rectangular solid (cuboid shape) of wax block with dimensions 66cm, 42cm, 21cm, 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.

Volume of wax in the rectangular solid = lbh = (66 × 42 × 21)cm3

Radius of cylindrical candle = r =
4.2
2
 cm = 2.1 cm

Height of cylindrical candle = h = 2.8 cm

Volume of candle = πr2h

=
22
7
 × ( )2 ×

Let x be the number of candles

Volume of x cylindrical wax candles =
22
7
 × × × × x

∵ Volume of x cylindrical candles = Volume of wax in rectangular shape

⇒
22
7
 × × × × x = × ×
⇒ x =
× × × 7
22 × × ×
=

Hence, the number of cylindrical wax candles that can be prepared is