Direction: In each of the following questions, there is a certain relationship between two given numbers on one side of (: :) and one number is given on another side of (: :) where another number is to be found from the given alternatives, having the same realtionship with this numbers of the given pair bear. Choose the best alternative.
- 
					 4 : 9 : : 8 : ?
 
- 
                        
- 2
 - 13
 - 31
 - 10
 
 
Correct Option: B
 As, 4 : 9 similarly 8 : 13
∴ ? = 13