Formula for mean

Dear Student,
Arithmetic means is the most commonly used measure of central tendency. It is the sum of the values of all observation divided by the number of observations.
There are following two formula for finding mean:
1. Direct method 
        Mean =   ΣX  
                        N
Where, ΣX =  Sum of all observations and N = Total number of observations

2. Assumed mean method
        Mean =  A +   Σdx  
                                N
    where A =  Assumed mean
            dx  =  (x-A)
             N  = Total Number of observation
3. The formula under discreet series
(a) Direct method
        Mean =        ΣFX   
                              N
    Where
          ΣFX =  sum of multiplication of frequency and observation
             N  =   Total number of observation

  (b) Assumed mean method
        Mean =  A +    ΣFdx  
                                   N 
Where
        ΣFdx = sum of multiplication of frequency with dx     
             dx = (X - A)
             N  =   Total number of observation
4. Continuous series formula
(a) Direct method 
        Mean =        ΣFM   
                              N
Where   M = Midpoint       
              N = ΣF
(b) Assumed mean method
       Mean = A +     ΣFdx  
 ​​​                            ​​​​ N
Where   N = ΣF
            dx = (M - A)

Regards,