# If x1, x​2, x3.....,xn are the means of n groups with n1 n2 n3......,nn number of observations respectively, then find the mean x of all the groups taken together

Dear Student,

We know :  Mean  = , So  We get

,

( Sum of observations )1 = n1x1  , Similarly we get

( Sum of observations )2 = n2x2

( Sum of observations )3 = n3x3
.
.
.
( Sum of observations )n = nnxn

Then ,

Mean of all group together = x  =                                    ( Ans )