Question

From the given Frequency distribution table, find the Average Class Mark.

$\begin{array}{cc}\text{Class Internal}& \text{Frequency}\\ 0-10& 2\\ 10-20& 8\\ 20-30& 12\\ 30-40& 7\\ 40-50& 9\\ 50-60& 4\\ 60-70& 5\end{array}$

Answer 1

First, we need to construct the Table with the Corresponding Class Mark.

$\begin{array}{ccc}\text{Class Internal}& \text{Class mark}& \text{Frequency}\\ 0-10& 5& 2\\ 10-20& 15& 8\\ 20-30& 25& 12\\ 30-40& 35& 7\\ 40-50& 45& 9\\ 50-60& 55& 4\\ 60-70& 65& 5\end{array}$

From the Given table we can see the class marks as - 5, 15, 25, 35, 45, 55, 65,

The Average Class mark = $\frac{5+15+25+35+45+55+65}{7}$

= $\frac{245}{7}$ = 35

Since , the number of terms are odd and the range is for continuous data,

without even calculating we can see that the Middle value is 35 which is the average.