Question

Find the mean for the following data

$$\begin{array}{cccccc}Class& 0-10& 10-20& 20-30& 30-40& 40-50\\ Frequency& 10& 9& 8& 17& 6\end{array}$$

Answer 1

$$\begin{array}{ccc}\text{Class Mark}& \text{Frequency}& f_i{x}_i\\ \text{5}& \text{10}& \text{50}\\ \text{15}& \text{9}& \text{135}\\ \text{25}& \text{8}& \text{200}\\ \text{35}& \text{17}& \text{595}\\ \text{45}& \text{6}& \text{270}\end{array}$$
$\sum f_i$=50
$\sum f_i{x}_i$ = 12500
Mean = $\frac{12500}{50}=25$