00:01
In this question we're given there are 100 mcq questions in the test.
00:06
Each question has five possible answers with only one is correct.
00:12
A student answers each question randomly.
00:15
Gonna let x be the number of correct answers out of 100 questions answered.
00:20
Now n, the number of trials will be 100.
00:24
In each trial we take a look at a question and see whether it's being answered correctly or not.
00:29
And so these 100 trials are identical, they're independent.
00:34
And in each trial there's only one or two possible outcomes, success or failure.
00:39
Success would be a question is answered correctly, failure would be it's not answered correctly.
00:44
And p, probability of success in a single trial, that's probability a question is answered correctly, would be 1 out of 5 or 0 .2.
00:55
So we have q which is the probability of failure in a single trial.
01:02
That will be 1 minus p which is 1 minus 0 .2 and there'll be 0 .8.
01:09
Now this p, probability of success in a single trial, is constant for all trials.
01:15
So x follows the binomial distribution n is 100, p is 0 .2.
01:26
N is 100 is greater than 50.
01:31
N times p which is taking 100 times 0 .2 and that is 20 is greater than 5.
01:39
Nq that is taking 100 times 0 .8 we get 80 and that is greater than 5...