Question

A and B are alloys of gold and copper prepared by mixing metals in the ratio 7: 2 and7: 11 respectively. If equal quantities of the alloys are melted to form a third alloy C, what will be the ratio of gold and copper in C?

• A. 7: 5
• B. 5: 7
• C. 8: 5
• D. 5:8

Answer 1

The correct option is A 7: 5

Since both alloys are mixed in the same ratio, we need only take the average.
Portion of gold in alloy $C=\frac{\frac{7}{9}+\frac{7}{18}}{2}=\frac{7}{12}$
Therefore, the ratio of Gold: Copper = 7: 5