00:01
For this exercise, we are told that a message goes through a series of servers in three separate steps.
00:08
For the first step, it can go through one of three servers.
00:12
For the second step, it can go through one of five servers.
00:16
For the third step, it can go through one of four servers before being sent to the recipient server.
00:25
And for part a, we were asked how many paths are possible.
00:29
This is a question where we can make use of the fundamental counting principle, which says that the number of ways of something occurring, when there are k1 ways of doing the first thing, k2 ways of doing the second thing, and k3 ways of doing the third thing is equal to the product of k1 times k2 times k3.
00:57
So in this case we're talking about the number of pathways to reach the recipient's server, and k1 is three.
01:06
There's three servers that the message can take in the first step.
01:13
K2 is 5 and k3 is 4...