Solution:
(i) Short – cut method
Here, 
(ii) Step – deviation method
Here, 
The following are the marks obtained by 70 boys in a class test:
![\[\begin{tabular}{|l|l|} \hline Marks & No. of boys \\ \hline $30-40$ & 10 \\ \hline $40-50$ & 12 \\ \hline $50-60$ & 14 \\ \hline $60-70$ & 12 \\ \hline $70-80$ & 9 \\ \hline $80-90$ & 7 \\ \hline $90-100$ & 6 \\ \hline \end{tabular}\]](https://www.learnatnoon.com/s/wp-content/ql-cache/quicklatex.com-6f1c4783754364f16013b5633c6dbb6a_l3.png "Rendered by QuickLaTeX.com")
(i) Short – cut method
(ii) Step – deviation method
Solution:
(i) Short – cut method
Here,
(ii) Step – deviation method
Here,
