Question

In 1 kg mixture of iron and carbon, 40% is carbon. How much iron should be added so that the proportion of carbon becomes 20%

Answer 1

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2 kg

Answer 2

Answer: 1 kg

Explanation:

Current proportion of carbon = 40%

Thus, mass of carbon in mixture = 0.4 kg

For the proportion of carbon to be 20%, the proportion of iron should be 80%.

Thus by unitary method,

New mass of iron = 0.4 x 4 = 1.6 kg

Hence mass of iron to be added = 1.6 - 0.6 = 1 kg