00:01
This exercise, we have this following component diagram.
00:07
The probability of components 1 and 2 working is 0 .9.
00:14
And the probability of components 3 and 4 working are 0 .8 each.
00:23
And so we were asked for the probability that the system works.
00:37
Now let's break this down into two sub -components or subsystems.
00:41
So we'll call this subsystem a and we'll call this subsystem b.
00:48
Since the subsystems are in parallel, we only need one of them to work for the system to work.
01:02
So we have this probability, and this is equal to the probability that this is equal to 1 minus, the probability that a does not work, and b does not work.
01:26
Now, since all components work independently of each other, this is equal to 1 minus the probability that a does not work, times the probability that b does not work.
01:48
Now, just as a subcalculation, the probability that a does not work is equal to the probability 1 does not work times the probability that 2 does not work, because for subcomponent a, they are in parallel, so we need both of them not to work, for a not to work.
02:23
And so this is 0 .1 times 0 .01, which is 0 .01...