Two vessels P and Q contain 62.5% and 87.5% of alcohol respectively. If 4 litres from vessel P is mixed with 6 litres from vessel Q, the ratio of alcohol and water in the resulting mixture is? Choose the most appropriate option:
A) 31 : 1	B) 31 : 4	C) 31 : 8	D) 31 : 9	E) 31 : 2

Rationale: "quantity of alcohol in vessel p = 62.5 / 100 * 4 = 5 / 2 litres quantity of alcohol in vessel q = 87.5 / 100 * 6 = 21 / 4 litres quantity of alcohol in the mixture formed = 5 / 2 + 21 / 4 = 31 / 4 = 7.75 litres as 10 litres of mixture is formed , ratio of alcohol and water in the mixture formed = 7.75 : 2.25 = 31 : 9 . answer : d"
Answer: D