00:01
So in this question we have to consider 10 questions.
00:04
Each one of them has like five choices.
00:07
So this means that you're going to get like this one question right here.
00:14
If you find like one of these five options.
00:18
So the probability that you get this question right is one out of five for each one of these questions.
00:24
So in item a, we should say what is the probability that the first question you get is the third one.
00:30
So this means that the first, imagine that he is the questions, the first, the second, and the third.
00:36
So the first one you got wrong.
00:40
So this means that instead of getting right, which is this probability, the probability of getting wrong is 4 divided by 5.
00:50
So this means that the first one you got wrong, so 4 divided by 5, which is the probability.
00:56
Then the second one you also got wrong.
00:59
So in this case, 4 divided by 5 again.
01:02
But like the third one you got right, so 1 divided by 5.
01:06
So these will be, in this case, the answer for the first part of this question.
01:13
Now for item b, you need to get five questions right out of 10.
01:19
So because now we are counting the number of questions that you got right, so here is the number of questions that.
01:25
That were like right here.
01:30
So let me just change here.
01:32
Basically, this means that we can say that x has a binomial distribution with two arguments.
01:41
So we have the number of questions and the probability of getting one question right.
01:47
So using this we can use the formula for the binomial distribution that says that the probability of x be equals to a little x is given by this formula, formula, the combination of 10, which is the number of questions, then you got x questions right.
02:03
Then you have the probability of getting a question right and the number of questions that you got right.
02:10
And the last, the other questions, you got all of them wrong.
02:14
So four divided by five...