00:01
We have a deck of cards and we have three events, a, b and c.
00:06
So event a, b and c, event a is select a king.
00:17
Event b is a jack or a queen.
00:24
Event c is select a heart.
00:30
So are these independent? so what does it mean to be independent? well, it has to meet this rule.
00:36
The probability of the a intersect b is equal to just multiplying the probabilities of these events separately.
00:46
So if the way you get the probability of both events happening is just multiplying the two separate probabilities together, then they are independent.
00:57
If there's something more complicated going on, they're influencing each other, it's not independent.
01:02
So let's go through these and have a look.
01:05
So you're selecting a card.
01:09
First we have a and b.
01:11
So what's the probability that you get both? well, zero.
01:19
You can't have both.
01:21
You can't have a card that's both a king and a jack or a queen.
01:26
So the probability of a intersect b is just zero.
01:35
Which means, well, the probability of a is a quarter, which you probably put those out.
01:41
Oops, no it's not.
01:42
It's 4 out of 52.
01:44
One out of 13.
01:45
There are four kings in the 52 card deck, so that's 4 out of 52.
01:51
There are four jacks and four queens, so that means 2 out of 13 for that...