An alloy of copper and zinc contains copper and zinc in the ratio 5 : 4. Another alloy of copper and zinc contains copper and zinc in the ratio 3 : 6. In what ratio should the two alloys be mixed so that the resultant alloy contains equal proportions of copper and zinc? Choose the correct choice from the following: A) 4 : 1 B) 6 : 1 C) 1 : 3 D) 2 : 1 E) 4 : 1
Let Alloy_1 be x units, and let Alloy_2 be y units.   So, fraction of copper in Alloy_1 = 5x/9, and fraction of zinc in Alloy_1 = 4x/9.   Similarly, fraction of copper in Alloy_2 = 3y/9, and fraction of zinc in Alloy_2 = 6y/9.   Mixing them, we get   copper = 5x/9 +3y/9; zinc = 4x/9 + 6y/9   So, 5x+3y = 4x+6y   -&gt; x = 3y   -&gt; x/y =1/3   So, they must be mixed in the ratio 1 : 3   Answer : 1 : 3
<result>C</result>
An alloy of copper and zinc contains copper and zinc in the ratio 5 : 4. Another alloy of copper and zinc contains copper and zinc in the ratio 3 : 6. In what ratio should the two alloys be mixed so that the resultant alloy contains equal proportions of copper and zinc?