Alloy A contains copper and zinc in the ratio 4 : 5 and alloy B contains…
20202020
Alloy A contains copper and zinc in the ratio 4 : 5 and alloy B contains copper and zinc in the ratio 7 : 2. A and B are taken in the ratio 7 : 4 and melted to form a new alloy. The percentage of copper in the new alloy is closest to:
- A.
67.5%
- B.
65.25%
- C.
56.57%
- D.
57.79%
Attempted by 36 students.
Show answer & explanation
Correct answer: C
Given:
Alloy A:
Copper : Zinc = 4 : 5
Copper % in A:
= 4/(4 + 5) × 100
= 4/9 × 100
= 44.44%
Alloy B:
Copper : Zinc = 7 : 2
Copper % in B:
= 7/(7 + 2) × 100
= 7/9 × 100
= 77.78%
A and B are mixed in the ratio 7 : 4.
Copper % in new alloy:
= (7 × 44.44 + 4 × 77.78)/(7 + 4)
= (311.08 + 311.12)/11
= 622.20/11
= 56.56%
≈ 56.57%