Question

Find the number of coins, 1.5 cm is diameter and 0.2 cm thick, to be melted to form a right circular cylinder of height 10 cm and diameter 4.5 cm.

Answer 1

Volume of one coin `=pi xx (1.5)^(2/4) xx 0.2`

Volume of cylinder`= pi xx (4.5)^2 xx 10 /4`

So number of coins to be melted

`="volume of cylinder"/"volume of each coin"`

`=(4.5/1.5) xx 10/0.2`

`= 9 xx 50`

` = 450`