00:01
Okay, we are told here the chance of success is 0 .5 and n number of trials is 12.
00:09
And i want to work out the chance and we get 7 successes.
00:13
Well, here we do it two ways.
00:15
First of all, the formula, i used to have 0 .5, the p value occurring seven times.
00:23
That means seven successes.
00:25
There are 12 trials, that means there must be 5 failures, and failure is also 0 .5.
00:35
So we have that.
00:37
So up here, success, 0 .5, so here failure, 1 minus that, also 0 .5.
00:48
And a number of ways of doing this is the binomial number, 12 .7.
00:53
And 12 -7 just means 12 factorial, 5 factorial, 7 factorial, which you can work out on a calculator.
01:08
And the whole thing, you can find the answer, and it'll be this.
01:13
Or the whole thing comes out to be 0 .193.
01:20
I mentioned in accuracy here, so 1933, that you can find.
01:23
By the way, this is e4 -2, 792.
01:31
It's one way of doing it.
01:33
A bit easier is to use ti -84 calculator and use the function binom pdf...