Question

Read the following bar graph and fill in the blanks:

The mean strength of class IX and X is______.

Answer 1

The total strength of class IX=$105$

The total strength of class X=$75$

Formula to calculate the mean is,

$$\begin{gathered} \mathrm{Mean}=\frac{\mathrm{Sum}\mathrm{of}\mathrm{all}\mathrm{observations}}{\mathrm{Total}\mathrm{number}\mathrm{of}\mathrm{observations}} \\ =\frac{105+75}{2} \\ =\frac{180}{2} \\ =90 \end{gathered}$$

Hence, mean strength of class IX and X is $90$