Give a quick stream of consciousness before answering the following question. The average of twelve numbers is 7. The average of first nine numbers is 6 and the average of last two numbers is 10. What is the middle number?
Options:
(A) A) 9
(B) B) 10
(C) C) 12
(D) D) 7
(E) E) 13
The total of twelve numbers = 12X7 = 84
The total of first 9 and last 2 numbers is = 9 X 6+2 X 10 = 74
So, the middle number is (84 - 74 ) = 10
The answer: (B).