What is the percentage of copper in X ?
For the next two (02) items that follow : X is an alloy of copper and zinc. Y is an alloy containing 80% of copper, 4% of zinc and 16% of tin. A fused mass of X and Y is found to contain 74% of copper, 16% of zinc and 10% of tin.
- A. 60%
- B. 64% ✓
- C. 66%
- D. 70%
Correct Answer: B. 64%
Explanation
Since X has no tin (it's only Cu and Zn), all tin comes from Y. Thus, 0.16 Y = 0.10 (X+Y) \implies 0.06 Y = 0.10 X, giving X/Y = 3/5. Let mass be 3k and 5k (total 8k). Copper equation: C_x(3k) + 0.80(5k) = 0.74(8k) \implies 3C_x + 4.0 = 5.92 \implies 3C_x = 1.92 \implies C_x = 0.64, which is 64%.
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