00:01
In this question, we're given a gas station claims that one out of three cars needs to have oil added, and we'll assume the claim is true.
00:09
Now, the next eight cars are considered.
00:12
I'm going to let x be the number of cars out of eight that needs oil.
00:16
Now, x follows the binomial distribution, of which there are four criterias.
00:20
First criteria, the number of trials, n is fixed and are identical.
00:24
In this case, there are eight cars, so n is eight.
00:27
So there are eight trials.
00:28
This trial is looking at a car, whether it needs.
00:30
Needs oil or not.
00:31
So the trials are all identical.
00:35
So the first criteria is fulfilled.
00:37
Second criteria, each trial is independent.
00:39
So each car, whether they need oil or not is independent on the other cars.
00:44
So second criteria is fulfilled.
00:46
Third criteria, each trial results in one and two outcomes, success and failure.
00:50
Now the success would be the cars need oil, a car needs oil.
00:54
The failure will be a car does not need oil.
00:56
So the third criteria is fulfilled.
00:58
Fourth the fourth criteria is the probability of success denoted by p remains the same from trial to trial.
01:04
In this case, probability of a single trial is probability of a car -needing oil, and there is one out of three, or p is one -third...