Q:
      
      
         
            
Three persons A, B and C are standing in a queue. There are five persons between A and B and eight persons between B and C. If there be three persons ahead of C and 21 persons behind A, what could be the minimum number of persons in the queue?
         
       
      
      
      
          
      
      
          Answer & Explanation
         Answer: C) 28         
         
Explanation: Three persons A, B, C can be arranged in a queue in six different ways, ie ABC, CBA, BAC, CAB, BCA, ACB. But since there are only 3 persons ahead of C, so C should be in front of the queue. Thus, there are only two possible arrangements, ie CBA and CAB.
 
We may consider the two cases as under:
Case I:  
 
Clearly, number of persons in the queue = (3+1+8+1+5+1+21=) 40
 
Case II:  
 
Number of persons between A and C                  
 
= (8 - 6) = 2   
 
Clearly number of persons in the queue = (3+1+2+1+21) = 28
 
Now, 28 < 40. So, 28 is the minimum number of persons in the queue.                                                     
 
 
       
      
      
      
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