WAEC Mathematics Question 2015 ( Essay Question One 1b )

1. (b) A Number is selected at random from each of the sets {2, 3, 4} and {1, 3, 5}. Find the probability that the sum of the two numbers is greater than 3 and less than 7.

 

SOLUTION

 

  

From the table above, the sum of numbers greater than 3 and less than 7 includes
























 
  

  
        +
  
  

  
           2
  
  

  
          3
  
  

  
          4
  
 
 
  

  
        1
  
  

  
         2,1
  
  

  
        3,1
  
  

  
        4,1
  
 
 
  

  
        3
  
  

  
         2,3
  
  

  
        3,3
  
  

  
        4,3
  
 
 
  

  
        5
  
  

  
         2,5
  
  

  
        3,5
  
  

  
        4,5
  
 

(3,1), (4,1), (2,3), (3,3) = 4

Therefore the probability that the sum of the two numbers is greater than 3 and less than 7 is given as:

 

Prob.(3<x<7) =   ANSWERED