91Ó°ÊÓ

The average number of engineers waiting in the line

L= Average number of engineers waiting in the line

N = Number of Engineers

F= Efficiency factor

F for S = 1 and

X = 0.125

From the Finite Queuing Table given in the

Thus, Efficiency factor (F) = 0.945.

$\begin{array}{l}\mathrm{L} = \mathrm{N}× \left(1- \mathrm{F}\right)\\     = 4×\left(1- 0.945\right)\\     = 0.22\end{array}$

Hence, the average number of engineers waiting in the line is 0.22

To get the average waiting time, compute the value of H.

H is the number of engineers to be helped.

The average number of engineers being helped,

$\begin{array}{l}\mathrm{H} = \mathrm{N} ×\mathrm{F} ×\mathrm{X}\\      = 4×0.945×0.125\\ \mathrm{H} = 0.475\end{array}$

Calculate the average time an engineer has to wait with the help of the given formula:

Average time an engineer has to wait

$\begin{array}{l}\mathrm{W} = \frac{\mathrm{LT}}{\mathrm{H}}\\       = \frac{0.22×1}{0.475}\\       =0.463 \mathrm{Hour}\end{array}$

Hence, the average time an engineer has to wait is 0.463 hours.

Service factor (X) = 0.125

Efficiency factor (F) = 0.945

Number of assistants (S) = 1

The value of D in the table is 0.362.

Therefore, the probability (D) that an engineer will have to wait in line for the specialist is D=0.362