Frequency Distribution of the Scores from a Mathematics Test Is

Multiple Choice

Frequency distribution of the scores from a mathematics test is given in the table below. Find the sample standard deviation.   $$\begin{array} { | l | l | l | l | } \hline \text { Interval } & \text { Midpoint } x & \text { Frequency } f & \text { Product } x f \\\hline 64.5 - 70.5 & & 4 & \\\hline 70.5 - 76.5 & & 7 & \\\hline 76.5 - 82.5 & & 7 & \\\hline 82.5 - 88.5 & & 5 & \\\hline 88.5 - 94.5 & & 2 & \\\hline 94.5 - 100.5 & & 6 & \\\hline\end{array}$$ Round your answer to the nearest whole number.

A) 12
B) 10
C) 18
D) 17
E) 8