|  
         X 
       | 
       
         -1 
       | 
       
         2 
       | 
       
         3 
       | 
       
         4 
       | 
    
|  
         P(X = x) 
       | 
       
         0.1 
       | 
       
         0.6 
       | 
       
         0.2 
       |