if xi's are the mid points of the class interval of grouped data, fi's are the correspondind frequinces and xu - Maths - Statistics

Question

if xi's are the mid points of the class interval of
grouped data, fi's are the correspondind frequinces and
xu is the mean,
then (sum of) fi( xi-xu)
is?

kiran middha · Accepted Answer

Mean = xu = $\frac{{Σ f}_{i} x_{i}}{{Σ f}_{i}}$ or xu $Σ f_{i} = Σ f_{i} x_{i}$ (1) Now, $Σ f_{i} (x_{i} - x^{u}) = Σ f_{i} x_{i} - x^{u} Σ f_{i} = x^{u} Σ f_{i} - x^{u} Σ f_{i} (f r o m (1)) = 0$

if xi's are the mid points of the class interval of grouped data, fi's are the correspondind frequinces and xu is the mean, then (sum of) fi( xi-xu) is?

if x_i's are the mid points of the class interval of grouped data, f_i's are the correspondind frequinces and x^uis the mean,

then (sum of) f_i( x_i-x^u) is?