In the Internet the TCPIP protocol suite is used for transmi

In the Internet, the TCP/IP protocol suite is used for transmitting packets of
information. The receiving TCP entity checks the packets for errors. If an error
is detected, it requests retransmission of the packet that is found to be in error.
Suppose that the packet error probability is 102 .
(a) What is the probability that the third packet requires retransmission?
(b) What is the probability that the tenth packet requires retransmission?
(c) What is the probability that there is a packet retransmission within the
rst 5 packets?
(d) Following on the lines of (c), how many packets are required in order for
the probability of retransmission to be equal to or greater than 0.1?

Solution

Probability of error 10^-2 means 1 error packet in 100 packets.

(a) Third packet requires retransmission means first two packets were correctly received.

So the required probability is=1/98

(b) Tenth packet requires retransmission means first 9 packets were correctly received.

So the required probability is=1/91

(c) 1/5