Cereal A is 10% sugar by weight, whereas healthier but less delicious Cereal B is 2% sugar by weight. To make a delicious and healthy mixture that is 3% sugar, what should be the ratio of Cereal A to Cereal B, by weight? Select:
A) 2 : 9
B) 2 : 7
C) 1 : 7
D) 1 : 4
E) 1 : 3

Rationale: 2 % is 1 % - point below 3 % and 10 % is 7 % - points above 3 % . the ratio of a : b should be 1 : 7 . the answer is c .
Answer: C