Question

250 students of class X of a school appeared in a test of 100 marks and the data about the marks secured is as below.

$$\begin{array}{cccccc}MarksSecured& 0-20& 20-40& 40-60& 60-80& 80-100\\ Numberofstudents& 20& 35& 65& 60& 70\end{array}$$

Answer 1

$$\begin{array}{ccc}\text{Class~Marks}& \text{Number~of~students}& f_i{x}_i\\ \text{10}& \text{20}& \text{200}\\ \text{30}& \text{35}& \text{1050}\\ \text{50}& \text{65}& \text{3250}\\ \text{70}& \text{60}& \text{4200}\\ \text{90}& \text{70}& \text{6300}\end{array}$$
$\sum f_i$=250
$\sum f_i{x}_i$ = 15000
Mean = $\frac{15000}{250}=60$