A certain box has 11 cards and each card has one of the integers from 1 to 11 inclusive. Each card has a different number. If 2 different cards are selected at random, what is the probability that the sum of the numbers written on the 2 cards is less than the average (arithmetic mean) of all the numbers written on the 11 cards?
Choose the correct choice
A) 1 / 11	B) 2 / 11	C) 2 / 33	D) 4 / 55	E) 5 / 66

Rationale: the average of the numbers is 6 the total number of ways to choose 2 cards from 11 cards is 11 c 2 = 55 . the ways to choose 2 cards with a sum less than the average are : { 1,2 } , { 1,3 } , { 1,4 } , { 2,3 } the probability is 4 / 55 the answer is d .
Answer: D