Three of the following four options are alike in a certain way and thus form a group. Which is the one that does NOT belong to that group?
(NOTE: Operations should be performed on the whole numbers, without breaking down the numbers into its constituent digits. E.g. 13 – Operations on 13 such as adding/subtracting/multiplying etc. to 13 can be performed. Breaking down 13 into 1 and 3 and then performing mathematical operations on 1 and 3 is not allowed.)
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 90 – 51 – 13.
Logic: (1st number + 3rd number) ÷ 2 = 2nd number
Except 90 – 51 – 13, All number pairs follow the same logic.
While 90 – 51 – 13 → (90 + 13) ÷ 2 = 103 ÷ 2 = 51.5 ≠ 51