# Computer Networking : A Top-down Approach

 Authors: James F. Kurose, Keith W. Ross ISBN: 9780132856201 Edition: 6
 Chapter: Computer Networks And The Internet Exercise: Problems Question: 5

### Question by Anonymous on 30 Mar, 2019 at 07:38 AM

Review the car-caravan analogy in Section 1.4. Assume a propagation speed of 100 km/hour.

a. Suppose the caravan travels 150 km, beginning in front of one tollbooth,passing through a second tollbooth, and finishing just after a third tollbooth. What is the end-to-end delay?

b. Repeat (a), now assuming that there are eight cars in the caravan instead of ten.

### Answer by Geroge on 12 Oct, 2017 at 05:17 AM

a)

Suppose the caravan travels 150 km, beginning in front of one tollbooth, passing through a second tollbooth, and finishing just after a third tollbooth.

Assume a propagation speedof 100 km/hour.

Delay time=total distance/propagation speed

=150/100km/hr

=1.5 hrs

Time for taken by 3 tollbooths to reach 10 cars= 2*3=6 minutes.

So, end-to-end delay = 1hr 30 minutes + 6 minutes

= 1hr 36minutes.

b)

assuming that there are 8 cars in the caravan instead of 10.

Time for taken by 3 tollbooths to reach 8 cars= 96*3=288 minutes=4 minutes 48 seconds.

So, end-to-end delay = 1hr 30 minutes + 4 minutes 48 seconds

= 1hr 33 minutes 48 seconds

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