Multiple choice

In two alloys A and B the ratio of zinc to copper is 4:5 and 2:7 respectively. Eighteen kg of the alloy A and 45 kg of the alloy B are mixed together to form a new alloy. What will be the ratio of Zinc and copper in the new alloy?

  1. $4:5$
  2. $2:5$
  3. $3:7$
  4. $2:3$
  5. $None of these$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Alloy A: 18 kg with Zn:Cu = 4:5, so Zn = (4/9)*18 = 8 kg, Cu = (5/9)*18 = 10 kg. Alloy B: 45 kg with Zn:Cu = 2:7, so Zn = (2/9)*45 = 10 kg, Cu = (7/9)*45 = 35 kg. New alloy: total Zn = 8+10 = 18 kg, total Cu = 10+35 = 45 kg. Ratio Zn:Cu = 18:45 = 2:5. Calculate each component separately before combining.