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?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is 4 ie 27 : 43.
Alloy A ratio = C : Z
3 : 4
B ratio = C : Z
5 : 9
After mixing, ratio = 2 : 3
Applying weighted average
C / total = 
= 27 / 70
c/z = 27 / (70 - 27) = 27 / 43