A zinc-copper alloy with 6 kg of pure zinc would contain 90% of zinc. The alloy with 3 kg of 90% zinc alloy contains 84% of zinc. Calculate the weight and percentage of zinc in the zinc-copper alloy.
Choose the correct option
A) 2.4 kg or 80%  B) 1.4 kg or 88%  C) 3.4 kg or 60%  D) 4.9 kg or 81.4%  E) 1.4 kg or 60%
Right Answer Explanation:   x : 6   y : 100   90   10 : 90 – y   (90-y)/6 = 10/x = ………..(1)   In the second case,   x 3   y 90   84   6 84-y   Therefore (84-y)/3 = 6/x ………..(2)   4.9 kg or 81.4%ividing (1) and (2)   =   270 – 3y = 840 – 10y   7y = 570   y = 81.4   x = 60/(90-80) = 60/10= 
<gadget id="calculator">60/10</gadget>
<output>6</output>
6 kg   Quantity of zinc in x= 81.4% of x   = 0.814 6   = 4.9 kg   Weight and percentage of zinc is 4.9 kg or 81.4%   4.9 kg or 81.4%
<result>D</result>
A zinc-copper alloy with 6 kg of pure zinc would contain 90% of zinc. The alloy with 3 kg of 90% zinc alloy contains 84% of zinc. Calculate the weight and percentage of zinc in the zinc-copper alloy.