00:01
We're looking at the probability of passing the driving test.
00:04
So first try, probability of success is 0 .75.
00:11
If they fail, probability of success on the second try is 0 .8.
00:18
Third try is 0 .7.
00:23
So for part a, what is the probability of failing the first and second test? so the probability of failing the first test is 0 .25.
00:33
The probability of failing the second is 0 .2.
00:38
We want both of these to happen.
00:40
In probability, when you want x and y, you multiply their probabilities.
00:48
So failing both is a probability of 0 .05.
00:59
Part b, failing three times in a row.
01:03
So now they fail the first test, 0 .25, and the second test, and the third test.
01:15
And when we multiply these together, we get 0 .0 .0 .15...