Solution P is 20 percent lemonade and 80 percent carbonated water by volume; solution Q is 45 percent lemonade and 55 percent carbonated water by volume. If a mixture of PQ contains 75 percent carbonated water, what percent of the volume of the mixture is P?  Choices:
A) 40 %
B) 50 %
C) 60 %
D) 80 %
E) 90 %

Rationale: "75 % is 5 % - points below 80 % and 20 % - points above 55 % . so the ratio of solution p to solution q is 4 : 1 . mixture p is 4 / 5 = 80 % of the volume of mixture pq . the answer is d ."
Answer: D