In What proportion must flour at $0.8 per pound be mixed with flour at $0.9 per pound so that the mixture costs $0.865 per pound?
Choose the correct answer.
A) 1 : 3  B) 1 : 2  C) 1 : 1  D) 2 : 1  E) 3 : 1

Rationale: using weighted average method : let x be the proportion in which the $ 0.8 per pound flour is mixed with $ 0.9 per pound flour . thus 0.8 * x + 0.9 * ( 1 - x ) = 0.865 0.9 – 0.1 x = 0.865 x = 0.35 thus ratio of both flours is 1 : 2 b
Answer: B