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How many coins of 1 cm in diameter and thickness of 1.2 cm need to be melted to form a cuboid with dimensions of 5 cm × 10 cm × 4 cm?

(a) 193

(b) 213

(c) 184

(d) 282

This question was addressed to me during an online exam.

This interesting question is from Conversion of Solid from One Shape to Another in division Surface Area and Volumes of Mathematics – Class 10

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Correct choice is (b) 213

Explanation: Volume of the cuboid = number of coins(volume of a coin)

lbh = number of coins(πr^2h)

5 × 10 × 4 = number of coins(3.14 × 0.5^2 × 1.2)

200 = number of coins(0.94)

number of coins = 213

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