In each of the following questions three of the given four are alike in a certain way and form a group .Which is the one that does not belong to that group in the following questions ?

Options

A. 999
B. 864
C. 343
D. 678

Answer

C

Explanation

Middle digit of a number = Average of the other two digits on the extreme.
i.e. `999rArr9=(9+2)/(2)=9`
`864rArr6=(8+4)/(2)=6`
`678rArr7=(6+8)/(2)=7`
`456rArr5=(4+6)/(2)=5`
But `343rArr4ne(3+3)/(2)=3`