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In two alloys the ratios of copper to tin are 3:4 and 1:6 respectively. If 7 kg. of the first alloy and…

In 7 kg of the 1st alloy (3:4), Copper \(= 3\text{ kg}\) and Tin \(= 4\text{ kg}\). In 21 kg of the 2nd alloy (1:6), Copper \(= 21 \times \frac{1}{7} = 3\text{ kg}\) and Tin…

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In two alloys the ratios of copper to tin are 3:4 and 1:6 respectively. If 7 kg. of the first alloy and 21 kg. of the second alloy are mixed together to form a new alloy, then the ratio of copper to tin in the new alloy is:

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Correct answer A

In 7 kg of the 1st alloy (3:4), Copper =3 kg= 3\text{ kg} and Tin =4 kg= 4\text{ kg}. In 21 kg of the 2nd alloy (1:6), Copper =21×17=3 kg= 21 \times \frac{1}{7} = 3\text{ kg} and Tin =21×67=18 kg= 21 \times \frac{6}{7} = 18\text{ kg}. In the combined alloy, Copper : Tin =(3+3):(4+18)=6:22=3:11= (3 + 3) : (4 + 18) = 6 : 22 = 3 : 11.

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