Concept:Use the alligation rule to find the ratio in which two ingredients are mixed to obtain a given mean value.Explanation:Metal A costs Rs. 8.40 per gm and is the dearer metal.Metal B costs Rs. 0.21 per gm and is the cheaper metal.Mean price of the mixture is Rs. 5.67 per gm.By alligation:Quantity of A : Quantity of B = (Mean price − Cost of B) : (Cost of A − Mean price)= (5.67−0.21):(8.40−5.67)= 5.46:2.73Divide both terms by 2.73:= 2:1
Answer:The metals must be mixed in the ratio 2:1.Therefore, option C is correct.
