00:01
In this case, it is said that a test has eight questions and you will answer any given question correctly with probability of p equals to 0 .9.
00:09
We need to determine the probability that you will get exactly two correct.
00:13
So first of all, let us consider a random variable x and let this random variable x denote the number of questions amongst those eight questions that you get correct.
00:22
Then this random variable x will follow a binomial distribution.
00:32
Now, the reason for this is that all four conditions for being a binomial distribution, are satisfied.
00:37
The first condition is that the number of trials n should be fixed.
00:40
Here, the test has eight questions, so the number of trials is fixed at n equals to eight.
00:45
The second condition is that all of the trials should be independent.
00:48
In this case, they are.
00:49
This is because whether you answer one question correctly, it does not affect in any way or form whether you answer the other questions correctly.
00:56
The third condition is that there should be exactly two outcomes.
00:59
One is a success and one is a failure...