Chapter 1, Problem P5P

a.

Explanation of Solution

• Cars propagate the tollbooths of length 75 km at a speed of 100km/hr and the tollbooth takes 12 seconds to service each car. There are 10 cars which take 12 × 10 = 120 seconds or 2 minutes to cross a tollbooth.
• At first tollbooth, the propagation delay of the cars is 45 minutes and reaches the second tollbooth after 2 + 45 = 47 minutes.
• The process repeats with second and third tollbooths and also takes 120 seconds or 2 minutes time for service.

Finally, the total propagation delay is calculated using following formula

$\begin{array}{c}\text{the}\text{propagation}\text{delay}\text{= time}\text{taken}\text{for}\text{service}\text{in}\text{first}\text{tollbooth+}\\ \text{time}\text{taken}\text{to reach}\text{second}\text{tollbooth}\end{array}$

b.

Explanation of Solution

• Cars propagate the tollbooths of length 75 km at a speed of 100km/hr and the tollbooth takes 12 seconds to service each car. There are 8 cars which take 12 × 8 = 96 seconds to cross a tollbooth.
• At first tollbooth, the propagation delay of the cars is 45 minutes and reaches the second tollbooth after 46 minutes and 36 seconds.
• The process repeats with second and third tollbooths and also takes 96 seconds time for service.

Finally, the total propagation delay is calculated using following formula