00:01
On your problem, you have 10 bills are selected, and the probability of an error is not given.
00:05
So this is something you need to find.
00:07
It must be given up above, or maybe in a previous question.
00:12
So this would end up being a binomial setting.
00:17
And let's go actually down to this last question.
00:19
And so the mean would be the number you have, n times p.
00:23
So it will be 10 times whatever that probability of success is, and your standard deviation will be the square root of n times p.
00:30
Times 1 minus p's will end up being that 10 times the square root of 10 times p times 1 minus p.
00:41
Now back up to these questions.
00:44
We know that this is a combination of 10 to 0 times the probability of your success to the 0th power, times the probability of the failure, which is 1 minus p to the 10th power.
00:57
And both of these are 1.
00:59
So you will end up taking.
01:01
Making that 1 minus p to the 10th power.
01:04
Now likewise, you can do the same thing here, that 10 choose 5 times p to the 5 times 1 minus p to the 5...