Fresh grapes contain 90% by weight while dried grapes contain 20% water by weight. What is the weight of dry grapes available from 25 kg of fresh grapes? Choose the correct choice from the following options:
A) 2 kg  B) 2.4 kg  C) 3.12 kg  D) 10 kg  E) none of these

Rationale: the weight of non - water in 25 kg of fresh grapes ( which is 100 - 90 = 10 % of whole weight ) will be the same as the weight of non - water in x kg of dried grapes ( which is 100 - 20 = 80 % of whole weight ) , so 25 â ˆ — 0.1 = x â ˆ — 0.8 - - > x = 3.12 answer : c .
Answer: C