One fourth of a solution that was 10% sugar by weight was replaced by a second solution resulting in a solution that was 20 percent sugar by weight. The second solution was what percent sugar by weight?
Choose one.
A) 65 %  B) 50 %  C) 22 %  D) 18 %  E) 8.5 %

Rationale: "say the second solution ( which was 1 / 4 th of total ) was x % sugar , then 3 / 4 * 0.1 + 1 / 4 * x = 1 * 0.20 - - > x = 0.5 . alternately you can consider total solution to be 100 liters and in this case you ' ll have : 75 * 0.1 + 25 * x = 100 * 0.20 - - > x = 0.5 . answer : b ."
Answer: B