i)Nyquest rate of x1   
 
    6000.  
 
 kHz   
 
   Nyquest rate of x2   
 
    2000.  
 
 kHz   
 
   Nyquest rate of x3   
 
    2000.  
 
 kHz   
 
   Nyquest rate of x4   
 
    2000.  
 
 kHz   
 
 iii)Signaling rate   
 
    12000.  
 
 Samples/sec   
 
 iv)Minimum channel bandwidth   
 
    6000.  
 
 Hz