A dessert recipe calls for 50% melted chocolate and 50% raspberry puree to make a particular sauce. A chef accidentally makes 15 cups of the sauce with 40% melted chocolate and 60% raspberry puree instead. How many cups of the sauce does he need to remove and replace with pure melted chocolate to make the sauce the proper 50% of each?
Answers.
A) 1.5
B) 2.5
C) 3
D) 4.5
E) 5

Rationale: we have 15 cups of sauce with 4040 choc and 6060 rasb cups of choc = 0.4 ∗ 15 = 6 cups of rasb = 0.6 ∗ 15 = 9 now let say we removed x cup of original mix and replaced with x cups of choc . therefore final number of cups of choc = 6 − 0.4 x + x now this number of cup should be 50 % of total = 15 / 2 = 7.5 therefore 6 − 0.4 x + x = 7.5 on solving x = 2.5 answer : b
Answer: B