The document describes observing the header of 3 consecutive packets going through a router to classify them as either video (v) or ordinary data (d). Various sets are defined based on properties of the 3 packet sequence, such as the second packet being video, alternating video and data, or having 1 or more video packets. It is then determined whether pairs of these sets are mutually exclusive (have no events in common), collectively exhaustive (have some events in common), or both. Specifically, sets A1 and B1 and sets A2 and B2 are mutually exclusive, while sets A3 and B3 are collectively exhaustive as they share the sequences vdd and ddv.

1. Quiz 1.2 Monitor three consecutive packets going through a Internet router. Based on the packet
header, each packet can be classified as either video (v) if it was sent from a Youtube server or as
ordinary data (d). Your observation is a sequence of three letters (each letter is either v or d). For
example, two video packets followed by one data packet corresponds to vvd. Write the elements
of the following sets: A1 = {second packet is video}, B1 = {second packet is data), {all packets
are the same}, B2 = {video and data alternate}, A2 = A3 = lone or more video packets}, B3 =
{two or more data packets). For each pair of events A 1 and B 1, A2 and B2, and soon, identify
whether the pair of events is either mutually exclusive or collectively exhaustive or both.
Solution
A 1 = { dvd, vvd,vvv, dvv }
A 2 = { vvv , ddd }
A 3 = { ddv, dvd, vdd, vvd,vdv, dvv, vvv}
B 1 = { vdv, vdd , ddv, ddd}
B 2 = { vdv, dvd }
B 3 = { vdd, ddv, dvd, ddd}
A 1 B 1 and A 2 B 2 are both mutually exclusive pairs are they do not have any event in common.
A 3 B 3 are collectively exhaustive pair as they have vdd and ddv in common