Question

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

Answer 1

radius of a coin=1.5/2=0.75
radius of cylinder=4.5/2=2.25
no. of coins required=

volume of cylinder/volume of coin

=7*22*2.25*2.25*10*7/22*0.75*0.75*0.2*7
=450coins

Answer 2

Hello!

First of all we have to find Volume of each coin.

Therefore,

Volume of each coin = π×(0.75)²×0.2 =0.1125π cm³

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Now,

Volume of melted cylinder = π× (2.25)²× 10 = 50.625π cm

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number of coin required =(volume of each coin)/ (volume of melted cylinder)

number of coins required = = 50.625π/0.1125π

no of coins = 450 coins

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         450 coins