Three of the following four number-pairs are alike in a certain way and thus form a group. Which number-pair does NOT belong to that group?
(NOTE: The relation should be found without breaking down the numbers into its constituent digits)
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 73, 79.
Option 1: 83, 97 → There is one prime number between 83 and 97, i.e., 89.
Option 2: 73, 79 → No prime number is between 73 and 79.
Option 3: 61, 71 → There is one prime number between them, i.e., 67.
Option 4: 31, 41 → There is one prime number between them, i.e., 37.