91Ó°ÊÓ

In a small community consisting of 153 families, the number of families that have k children \(\left( {k = 0,1,2,......} \right)\) is given in the following table:

Assuming that all families with four or more children have only four children, the above table is modified as follows:

Then, the mean is calculated as:

\(\begin{aligned}{c}Mean &= \frac{{\sum {{x_i}{f_i}} }}{{\sum {{f_i}} }}\\ &= \frac{{297}}{{153}}\\ &= 1.94\\ \simeq 2.\end{aligned}\)

Therefore, on an average, there exist 2 children per family.

Here, the median number of children is the class for which the cumulative frequency is greater than or equal to \(\frac{{153}}{2} = 76.5\).

Then, from the table above, it can be concluded that the median number of children per family is 2.

Here, the assumption that all families with four or more children have only four children has not been used because it does not fall into the median class. Hence, it does not affect the median value at all.