00:01
For this exercise, we are told that a certain type of computer has defects at a rate of 0 .1%.
00:10
And we're asked to consider a sample of size 10 ,000.
00:15
So our sample size is 10 ,000.
00:21
And the probability of a defect is 0 .1%, which equals 0 .001.
00:36
Now for part a, we are asked to find the expected value and the standard deviation on the number of computers in our sample, that have the defect.
00:47
So if the random variable x is the number of computers with the defect, then we can say that x is a binomial random variable based on a sample of 10 ,000 and a probability of success of 0 .001.
01:19
So that is each computer is a bernoulli trial, either a success or a failure.
01:24
The probability of success is constant for each computer, and we have a sample of 10 ,000.
01:29
For a binomial random variable, the expected value is n times p, which gives us 10, and the standard deviation is equal to the square root of n times p times 1 minus p, and this comes out to 3 .16.
02:17
So we have our expected value and our standard deviation...