00:01
We are wondering about the probability that one and only one engine will survive.
00:05
In other words, we're looking for the probability that out of four tests, we only have one s, meaning one survival.
00:11
To do this, we need to know the number of samples that meet our criteria over the total number of samples.
00:16
As stated in the previous problem, the total number of samples in our sample space is 2 to the 4th, because every test has two possible outcomes.
00:24
That means our sample space contains 16 solutions.
00:29
Now let's consider how many meet our criteria.
00:32
We need one and only one to survive.
00:34
You could work this out by hand and list out your possibilities.
00:38
For example, we could have this, one survival followed by three fails...