Give stream of consciousness and then the final answer. There are a total of 15 numbers with an average of 11. The average of first seven numbers is 14 and the average of last seven numbers is 6. What is the middle number?
Options:
(A) 31
(B) 24
(C) 29
(D) 25
(E) 21
The total of 15 numbers = 15X11 = 165
The total of first 7 and last 7 numbers is = 7 X 14+7 X 6 = 140
So, the middle number is (165 - 140 ) = 25
The final answer: (D).