Question 82
A merchant has 6 barrels with capacities of 15, 16, 18, 19, 20 and 31 litres. Five of them are full of wine and only one is full of beer. The merchant keeps the barrel of beer for himself and sells all the barrels of wine to two different people, without splitting their contents. If one of the two buyers has bought exactly twice as much wine as the other, how many litres does the barrel of beer contain?
(A) 16
(B) 18
(C) 19
(D) 20
(E) 31 .
(A) 16
(B) 18
(C) 19
(D) 20
(E) 31 .