What we know is that, Batch A has gloss finish percentage of G% by volume and B has a gloss finish percentage of H% by volume.
M litres of A is combined with N litres of B and we have to find gloss finish percentage by volume of the mixture.
We are also given 2 statements,
(1) The ratio of G to H is 7 to 5
(2) The ratio of M to N is 3 to 4
We know that,
Mixture % = (MG + NH) / M + N
Statement (1),
The ratio of G to H is 7:5
=> We now know the relative concentration , but not the amount used
Statement (2),
The ratio of M to N is 3:4
=> We now know the relative volumes, but not the concentrations
Combining (1) and (2),
Lets say,
G = 7x , H = 5x
M = 3y , N = 4y
Mixture = (3y * 7x + 4y*5x) / 3y + 4y = 41xy / 7y = 41x / 7
=> The mixture percentage is unknown since we dont know what x is here too
Thus,
E. The two statements together are not sufficient