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The waiting times of customers are given under two categories: single customer line and individual customer line.

The coefficient of variation is a percentage of change in the standard deviation measure over the mean of data values.

$C.V.=\frac{s}{\stackrel{炉}{x}}脳100$

, where

$s$is the sample standard deviation;

$\stackrel{炉}{x}$is the sample mean.

The mean waiting time for a single customer line is calculated as shown below:

$$\begin{gathered} {\stackrel{炉}{x}}_1=\frac{{鈭�}_{i=1}^{n_1}{x}_{1i}}{n_1} \\ =\frac{\left(390+396+...+462\right)}{10} \\ =429.0 \end{gathered}$$

Thus, the mean waiting time for a single customer line is 429.0 seconds.

The mean waiting time for individual customer lines is calculated as follows:

$$\begin{gathered} {\stackrel{炉}{x}}_2=\frac{{鈭�}_{i=1}^{n_2}{x}_{2i}}{n_2} \\ =\frac{\left(252+324+...+600\right)}{10} \\ =429.0 \end{gathered}$$

Thus, the mean waiting time for individual customer lines is 429.0 seconds.

The standard deviation for waiting time for a single customer line is given as follows:

$$\begin{gathered} s_1=\sqrt{\frac{{鈭�}_{i=1}^n{\left(x_{1i}-{\stackrel{炉}{x}}_1\right)}^2}{n_1-1}} \\ =\sqrt{\frac{{\left(390-429.0\right)}^2+{\left(396-429.0\right)}^2+...+{\left(462-429.0\right)}^2}{10-1}} \\ =28.6 \end{gathered}$$

Thus, the standard deviation for waiting time for a single customer line is 28.6 seconds.

The standard deviation for waiting time for individual customer lines is given as follows:

$$\begin{gathered} s_2=\sqrt{\frac{{鈭�}_{i=1}^{n_2}{\left(x_{2i}-{\stackrel{炉}{x}}_2\right)}^2}{n_2-1}} \\ =\sqrt{\frac{{\left(252-429.0\right)}^2+{\left(324-429.0\right)}^2+...+{\left(600-429.0\right)}^2}{10-1}} \\ =109.3 \end{gathered}$$

Thus, the standard deviation for waiting time for individual customer lines is 109.3 seconds.

The coefficient of variation for waiting time for a single customer line is computed as follows:

$$\begin{gathered} C{V}_1=\frac{s_1}{{\stackrel{炉}{x}}_1}脳100 \\ =\frac{28.6}{429}脳100 \\ =6.7\% \end{gathered}$$

Therefore, the coefficient of variation for waiting time for a single customer line is equal to 6.7%.

The coefficient of variation for waiting time for individual customer lines is computed as follows:

$$\begin{gathered} C{V}_2=\frac{s_2}{{\stackrel{炉}{x}}_2}脳100 \\ =\frac{109.3}{429}脳100 \\ =25.5\% \end{gathered}$$

Therefore, the coefficient of variation for waiting time for individual customer lines is equal to 25.5%.

The coefficient of variation for thewaiting time of individual customer lines isgreater than the coefficient of variation forwaiting time for individual customer lines by a large margin.

Hence, the waiting time for individual customer lines varies more than for a single customer line.