  
 (a)arithmetic mean(in V)=   
 
    12.65  
 
 (b)value of deviation(in V)=   
 
    0.15  
 
  - 0.45  
 
  - 0.15  
 
    0.45  
 
    0.25  
 
  - 0.25  
 
 (c)average deviation=   
 
    0.2833333  
 
 (d)standard deviation(in V)=   
 
    0.3201562  
 
 (e)variance(in V)=   
 
    0.1025  
 
 (f)probable error of one reading(in V)=   
 
    0.0691363  
 