Number analogy section deals with two types of questions:
I. Choosing a similarly related pair as the given number pair on the basis of the relation between the numbers in each pair.
II. Choosing a number similar to a group of numbers on the basis of certain common properties that they possess.
Given set : (9, 15, 21)
Justification: In each set, 1st number + 3rd number / 2 = 2nd number.