Find the missing number pair in the following series.
(2, 4), (3, 9), (5, 25), (7, 49), ?, (13, 169)
Show answer & explanation
Correct answer: B
Explanation
Given series:
(2, 4), (3, 9), (5, 25), (7, 49), ?, (13, 169)
Pattern in the first numbers of each pair:
The first numbers are: 2, 3, 5, 7, ?, 13.
These are prime numbers in ascending order.
The missing prime number between 7 and 13 is 11.
So, the first number of the missing pair is 11.
Pattern in the second numbers of each pair:
The second numbers are: 4, 9, 25, 49, ?, 169.
These are perfect squares of the first numbers:
22=4
32=9
52=25
62=36
72=49
112=121
132=169
So, the second number of the missing pair is 121.
The missing pair is (11, 121).
Hence, the correct answer is option (2).