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There are two alloys of copper and zinc. In the first alloy, the ratio of copper to zinc is 3 : 4 and in the second alloy the ratio of copper to zinc is 6 : 1. In what proportion should these two alloys be mixed, so that a new alloy containing equal parts of copper and zinc may be obtained?

A) 5 : 1
B) 7 : 2
C) 6 : 3
D) 4 : 3

Correct Answer:

A) 5 : 1

Description for Correct answer:
In the 1st alloy, the ratio of copper : zinc is 3 : 4, i.e, the proportion of copper In the first alloy = \( \Large \frac{3}{7} \)
In the 2nd alloy, the ratio of copper: zinc is 6: 1, i.e., the proportion of copper in the 2nd alloy = \( \Large \frac{6}{7} \)
The resultant alloy has copper and zinc in the ratio 1:1. Therefore, copper will be 1/2 of It. Now, the question can be solved in one of the two ways.
Method 1. Let 'a' parts of alloy 1 and 'b' parts of alloy 2 be mixed to obtain the resultant alloy.
Therefore, the amount of copper in the resultant alloy will be
\( \Large \frac{3}{7}a+\frac{6}{7}b=\frac{1}{2} \) ... (1)
Similarly, the amount of zinc in the resultant alloy will be
\( \Large \frac{4}{7}a+\frac{1}{7}b=\frac{1}{2} \) ... (2)
Solving equations (1) and (2), we get = \( \Large \frac{5}{6} \) and b = \( \Large \frac{1}{6} \)
or the ratio in which they should be mixed = 5 : 1

Part of solved Mixture and Allegation questions and answers : >> Aptitude >> Mixture and Allegation

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Similar Questions

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