Question

Two alloys containing copper and iron in the ratios 5: 8 and 5 : 3 are melted in equal quantities. The ratio of iron to copper in the resulting alloy is

• A. 103: 105
• B. 15 : 24
• C. 105 : 103
• D. 19 : 21

Answer 1

The correct option is C 105 : 103

Let 100 gm of alloy A and 100 gm of alloy B
Copper in alloy A=$\frac{5}{13}\times 100$
Iron in alloy A=$\frac{8}{13}\times 100$
Copper in alloy B=$\frac{5}{8}\times 100$
Iron in alloy B=$\frac{3}{8}\times 100$
Copper in alloy C=$\frac{500}{13}+\frac{500}{8}=\frac{10500}{104}$
Iron in alloy C=$\frac{800}{13}+\frac{300}{8}=\frac{10300}{104}$
Ratio of copper and iron in alloy C=$\frac{10500}{104}:\frac{10300}{104}$
$105:103$