00:02
All right, so this question asks us some questions about a binomial distribution with 10 trials, each having a success rate of 0 .1.
00:12
So, part a asks for probability that we get zero successes out of 10.
00:21
So how can that happen? well, there's only one way that can happen, and that is if you get a failure.
00:31
10 times in a row, which is just 0 .9 to the 10th power, which works out to be 0 .349.
00:42
All right.
00:46
Part b asks, what is the probability that you get exactly two successes? and that we can plug into the binomial distribution formula.
00:57
So that is 10 choose 2 times probability of success times to the power of two successes times probability of failure to the number of failures and that works out to be 0 .194 which alternatively, if you have a ti84, that's binomial pdf of 10 .1 and 2, which will give the same answer.
01:43
All right.
01:47
Part c.
01:49
It wants probability that x, that x, is less than or equal to 2, which that's equal to probability that x equals 0 plus probability x equals 1 plus probability that x equals 2.
02:16
Which you can do this by plugging each of these numbers into the binomial formula like we did for part b.
02:24
Or if you have a t -i -84, you can just do binomial cdf, c because it's cumulative, 10 trials, 0 .1 probability of success, and we want to sum all the probabilities up to 2.
02:44
And that works out to be 0 .930...