Concept of “Alligation”-07

Question: If 2 kg. of metal, of which 1/3 is zinc and the rest of copper, be mixed with 3 kg of metal, of which 1/4 is zinc and the rest is  copper, what is the ratio of  zinc to copper ?   [Ans. (b) 17 : 43]   

(a) 7 : 53  (b)  17 : 43  (c)19 : 41  (d) data inadequate (e) none of these

Solution: We avoid the method of "Alligation" for this question. And solve by the following method:

Detailed Explanation:

Concept: We can take the quantities of metals anything without altering the ratio.

LCM of 3 and 4 is 12

So, let 2×12 and 3×12 i. e., 24 kg and 36 kg are the weights of two metals.

Quantity of zinc = 1/3^rd of 24 kg + 1/4^th of 36 kg = 8 kg + 9 kg = 17 kg

Quantity of Cupper = (60 – 17) kg = 43 kg

Ratio of Zn: Cu = 17:43 Ans.