Cream costs twice as much as skim milk. A certain brand of milk is 2/5 cream and 3/5 skim milk. What fraction of the cost of this brand is due to the cream?
Pick one: A) 2/7 B) 3/7 C) 4/7 D) 3/5 E) 2/5
Let x be the cost of the skim milk in the mixture.   The cost of the cream is (2/3)*x*2 = 4x/3.   The total cost is x+4x/3 = 7x/3 and the fraction due to the cream is (4x/3) / (7x/3) = 4/7   The answer is 4/7.
<result>C</result>
Cream costs twice as much as skim milk. A certain brand of milk is 2/5 cream and 3/5 skim milk. What fraction of the cost of this brand is due to the cream?