Took the approach of setting up equations and then substituting the given values. Either statement individually is not sufficient since there are 2 variables X and Y.
Considering both the statements together, we get
Total weight of the new solution = 80+X = 80+80 =160
New concentration of acid = (1/Y) = 1/2
Since initial concentration of neither the water nor the acid is given we will be unable to solve the equations. Eg. if initial concentration of acid was say 40 gms then new concentration will be 20 whereas if initial conc of acid was 60 then new would be 30.
Thus I chose the statement E as the answer. Took me a minute and a half though. Will work on improving my speed.
My attempt to capture my B-School Journey in a Blog : tranquilnomadgmat.blogspot.com
There are no shortcuts to any place worth going.