Multiple choice

The ratios of copper to Zinc in alloys A and B are (3:4) and (5:9) respectively. A and B are taken in the ratio (2:3) and melted to form a new alloy C. What is the ratio of copper to Zinc in C?

  1. $8:13$
  2. $3:5$
  3. $9:11$
  4. $27:43$
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D Correct answer
Explanation

For Alloy A (Cu:Zn = 3:4), in 2 units: Copper = 2 × 3/7 = 6/7, Zinc = 2 × 4/7 = 8/7. For Alloy B (Cu:Zn = 5:9), in 3 units: Copper = 3 × 5/14 = 15/14, Zinc = 3 × 9/14 = 27/14. Total Copper = 6/7 + 15/14 = 27/14. Total Zinc = 8/7 + 27/14 = 43/14. Therefore, ratio in C = 27:43. Option A (8:13), B (3:5), and C (9:11) are incorrect. The key is to calculate the actual quantities of each metal separately.

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