Example M.N. Elhance’s earnings for the past week were:
Monday $ 450
Tuesday $ 375
Wednesday $ 500
Thursday $ 350
Friday $ 270
Find his average earning per day.
Solution:
n = 5
\ Arithmetic mean =
Therefore, Elhance’s average earning per day is $389.
Shortcut Method :
Sometimes the values of x are very big and in that case, to simplify the calculation the shortcut method is used. For this, first you assume a mean (called as the assumed mean). Let it be A. Now find the deviations of all the values of x from A. We now get a new variable u_{i} = x_{i}  A
Now find
then
Example The expenditure of ten families
in dollars are given below :
Family : A B C D E F G H I J
Expenditure : 300 700 100 750 500 80 120 250 100 370
(in dollars).
Calculate the Arithmetic mean.
Solution: Let the assumed mean be $ 500. (as. = assume)
