# Calculate standard deviation of marks secured by 100 examinees in the examination: \begin{tabular}{|l|c|c|c|c|c|c|c|c|} \hline Marks & $10-20$ & $20-30$ & $30-40$ & $40-50$ & $50-60$ & $60-70$ & $70-80$ & $80-90$ \\ \hline Number of Examinees & 19 & 3 & 2 & 49 & 24 & 2 & 0 & 1 \\ \hline \end{tabular} (Ans. $\sigma=14.9$ )

Calculate standard deviation of marks secured by 100 examinees in the examination: \begin{tabular}{|l|c|c|c|c|c|c|c|c|} \hline Marks & $10-20$ & $20-30$ & $30-40$ & $40-50$ & $50-60$ & $60-70$ & $70-80$ & $80-90$ \\ \hline Number of Examinees & 19 & 3 & 2 & 49 & 24 & 2 & 0 & 1 \\ \hline \end{tabular} (Ans. $\sigma=14.9$ )