Question

Read the following bar graph and fill in the blanks:

The mean strength of classes VII, IX and X is______.

Answer 1

The total strength of class VIII$=$$90$

The total strength of class IX$=$$105$

The total strength of class X$=$$75$

Formula of calculating mean ,

$$\begin{gathered} \mathrm{Mean}=\frac{\mathrm{Sum}\mathrm{of}\mathrm{all}\mathrm{observations}}{\mathrm{Total}\mathrm{number}\mathrm{of}\mathrm{observations}} \\ =\frac{90+105+75}{3} \\ =\frac{270}{3} \\ =90 \end{gathered}$$

Hence, mean strength of classes VII, IX and X is 90.