Let be the mean of x1, x2, …., xn and
be the mean of y1, y2, …yn. If
is the mean of x1, x2, …., xn, y1, y2…, yn, then
= ?
(given)..............(i)
(given)..............(ii)
Now, their combined mean is,
From equation (i) and eq.(ii)..
= )