You are given the values 5 items as 4, 6, 8,10,12.
(i) In the above example if mean is increased by 2, then what happens to the individual observations if all are equally affected.
(ii) If first three items increase by 2, then what would be the value of the last two items so that mean remains the same.
(iii) Replace the value 12 by 9 to what happen to the arithmetic mean comment.
(i) All the observation will be increase by 2 as it is clear from below :
Suppose increased in all the individual observations = X
Hence value of each individual observation will be increased by two
Suppose decrease in the value of last two observation = X
Hence New values will be =
Hence the value of last two items will be increased by 3.
(ii) 
of new values of observation
It shows that arithmetic mean is affected by extreme values.
