Question

If x_i's are the midpoints of the class intervals of a grouped data, f_i's are the corresponding frequencies and `barx` is the mean then `sumf_i(x_i - barx) = ?`

Options

• 1

• 0

• –1

• 2

Answer 1

0

Explanation:

By definition `barx = (Σf_ix_i)/N`.

So `Σ f_i(x_i - barx) = Σf_ix_i - Σf_ibarx`

= `Nbarx − Nbarx`

= 0