Q4 of 52 Page 160

A metal parallelopiped of measures 16 cm × 11cm × 10 cm was melted to make coins. How many coins were made if the thickness and diameter of each coin was 2 mm and 2 cm respectively?

Volume of parallelepiped, VP = Product of its three dimensions


⇒ VP = 16 × 11 × 10


⇒ VP = 1760 cm3


Thickness of coin, t = 2mm = 0.2 cm


Diameter of coin = 2 cm


⇒ Radius of Coin, r = 1 cm


Volume of one coin, VC = πr2t



⇒ VC = 0.6285 cubic cm


Let the number of coins made be ‘n’


⇒ VP = n × VC



⇒ n = 2800


∴ 2800 coins are made.


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