In each of the following questions, two numbers are given which follow a certain logical or arithmetic relationship. Identify the same pattern and apply it to find the missing number in the second pair. Choose the correct option from the given alternatives.
25 : 30 :: 36 : ?

Given: 25 : 30 :: 36 : ?

Logic: 1st number + $$\sqrt {1st number}$$ = 2nd number

For, 25 : 30

25 + $$\sqrt {25}$$ = 30

25 + 5 = 30

30 = 30

Similarly,

36 : ?

36 + $$\sqrt {36}$$ = ?

36 + 6 = ?

? = 42

Thus, correct option is (b).