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 monthly telephone bills (in dollars) . $\begin{array}{c|c}\text { Bill (in \$) } & \text { Frequency } \\\hline 50-52 & 2 \\53-55 & 5 \\56-58 & 12 \\59-61 & 19 \\62-64 & 7\end{array}$

A) $\$ 3.11$
B) $\$ 58.60$
C) $\$ 93.12$
D) $\$ 9.65$