Three bags whose volumes are in the ratio of 3 : 5 : 7 are full of lime and silica. In the 1st bag the ratio of lime and silica is 5 : 1, in 2nd bag the ratio is 7 : 3 and in the 3rd bag the ratio is 3 : 4. All the three mixtures are mixed in another bag. Find the ratio of lime and silica in the final mixture.
1
4 : 3
2
3 : 2
3
3 : 4
4
2 : 3
5
2 : 1