The Following Frequency Distribution Shows the Time (In Minutes) That $$\begin{array} { l l } \text { Time } & \text { Frequency } \\20 - 39 & 2 \\40 - 59 & 4 \\60 - 79 & 6 \\80 - 99 & 4 \\100 - 119 & 2\end{array}$$

Essay

The following frequency distribution shows the time (in minutes) that a sample of students uses the computer terminals per day. $$\begin{array} { l l } \text { Time } & \text { Frequency } \\20 - 39 & 2 \\40 - 59 & 4 \\60 - 79 & 6 \\80 - 99 & 4 \\100 - 119 & 2\end{array}$$ ​
a.
Compute the mean.
b.
Compute the variance.
c.
Compute the standard deviation.
d.
Compute the coefficient of variation.