00:01
For this exercise, we are told that the probability of a defective chip is 0 .003.
00:08
And the manufacturer sells the chips in batches of 500.
00:12
So we have 500 chips in a batch.
00:15
For each chip, the probability of being defective is 0 .003.
00:19
And then we are asked some probabilistic questions about the number of chips that are defective in the batch.
00:25
So let's let x be the number of defective chips in the batch.
00:35
Now, i don't know if you covered the number of defective chips in the batch.
00:37
Binomial distributions or binomial random variables in this course.
00:41
But if you have, you should point out that x is a binomial random variable.
00:58
And for part a, we're asked how many defective chips would you expect in the batch? so the question is what is the expected value of x? and for the binomial random variable, that is n times p.
01:21
And this is one and a half, which i can see you have entered in your answer and gotten correct.
01:27
B, what is the probability that none of the chips are defective in the batch? what is the probability that x is equal to 0? we need all of them to not be defective.
01:40
The probability of being defective for an individual chip is 1 minus 0 .003, that's 0 .997.
01:51
For all of them to not be defective, it's 0 .997 times .997 500 times...