00:01
Okay, i select three cards one of the time.
00:04
What i want is a king first, a diamond second, a diamond third.
00:09
Well, there are two ways to do this.
00:12
And the first way, if the first card is the king of diamonds, that's a one chance from 52, then to get a diamond next will be 12 out of 51.
00:30
There are 12 diamonds left in the pack.
00:34
Diamond again, 11 out of 50.
00:38
That's if the first card is a king of diamonds.
00:41
And this i can work out.
00:44
I'll just do it.
00:45
12 times 11 is 132 over 52.
00:53
52 times 51 times 50 is 136.
01:02
0.
01:04
Now if the first card is not a diamond, king of diamonds, so not king of diamonds, but a king, which means three chances from 52, then a diamond here will be 13 out of 51, there are 13 diamonds left.
01:31
Then it would be 12 diamonds left out of 50.
01:37
Comes 13 times 12 times 3, 4168 over 1 3, 132, 600.
01:52
So now all you do is add up these two and get the answer you need.
01:57
So 468 plus 132 is 600 out of 1 ,3 ,600.
02:09
And that i can reduce down, i expect.
02:15
Yes, that becomes 1 over 2 to 1.
02:22
That's the answer.
02:26
Okay, next question.
02:29
We are told p of a is 0 .2, p of b, 0 .3, p of a and b is 0 .12.
02:36
So the strong event diagram here.
02:41
Here is event a, here is event b.
02:45
We're told that p of a and b is 0 .12.
02:50
That's in the middle.
02:51
We know p of a is 0 .2 and not the entire circle which means here must be 0 .08 .1 .2 plus 0 .08 is 0 .2.
03:05
We know here is 0 .3...
