Approximate the Variance and Standard Deviation of a Variable from Grouped

Multiple Choice

Approximate the Variance and Standard Deviation of a Variable from Grouped Data
-For the following data set, approximate the sample standard deviation of unused vacation days . $\begin{array}{c|c}\text { Days } & \text { Frequency } \\\hline 1-2 & 9 \\3-4 & 22 \\5-6 & 28 \\7-8 & 15 \\9-10 & 14\end{array}$

A) $2.4$ days
B) $5.5$ days
C) $3.5$ days
D) $5.9$ days