Question

In the formula, `barx = {A + (sumf_i d_i)/(sumf_i)}` for finding the mean of the grouped data, the d_i's are the deviations from A of ______.

Options

• lower limits of the classes

• upper limits of the classes

• midpoints of the classes

• none of these

Answer 1

In the formula, `barx = {A + (sumf_i d_i)/(sumf_i)}` for finding the mean of the grouped data, the d_i's are the deviations from A of midpoints of the classes.

Explanation:

In the assumed-mean formula `barx = A + (sumf_id_i)/(sumf_i)` we have d_i = x_i – A and for grouped data x_i are the class midpoints (class‑marks). Therefore the d_i are the deviations of the class midpoints from A.