Q:
      
      
         
            
Consider two-digit numbers which remain the same when the digits interchange their positions. What is the average of such two-digit numbers?
 
         
       
      
      
      
          
      
      
          Answer & Explanation
         Answer: C) 55         
         
Explanation: All such 2 digit numbers are 11,22,33,44....... upto 99
Forms an AP
So sum = n/2(a+l)
= 9/2(11+99)
Average = sum/9 = ½(11+99) = 55
 
       
      
      
      
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