# A silver cuboid of dimensions 5.5 cms × 5 cm × 4.2 cms is melted to form circular coins

A silver cuboid of dimensions 5 cms × 5 cm × 4.2 cms is melted to form circular coins of diameter 1.75 cms and thickness 4 mm. Then the number of coins made from the silver metal is (Take π = 22/7)

1. 120
2. 80
3. 60
4. 12
Anurag Mishra Professor Asked on 21st April 2016 in
1 Answer(s)

Answer: (1) 120

Solution:-
The dimensions of a silver cuboid = 5.5 cm, 5 cm & 4.2 cm
Then, the volume of the silver cuboid = 5.5 x 5 x 4.2
= 115.5 cm cube

The diameter of a silver coin = 1.75
Then, the diameter of silver coin = 1.75/2
= 0.875
And the thickness of silver coin = 4 mm
So, the volume of a silver coin = 22 x  (0.875)^2 x 0.4/7
= 22 x 0.765625 x 0.4/7
= 0.9625 cm cube

Thus, the number of silver coin in a silver cuboid = 115.5/0.9625
= 120

Hence, the correct answer is option (1) 120.

Anurag Mishra Professor Answered on 21st April 2016.

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