**Q.) A and B two alloys of gold and copper prepared by mixing metals in the ratio 7:2 and 7:11 respectively.If equal quantities of the alloys are melted to form a third alloy C , the ratio of gold and copper in C will be **

1)5:7

2)7:5

3)8:9

4)9:5

Solution :

let the quantity of each alloy A and B be X kg. mixed to form alloy C.

gold in A =

copper in A =

gold in B =

copper in B =

Total gold in C =

Total copper in C =

Hence , the ratio of gold and copper in C = = 7:5

Hence Option(2)