00:01
One card is drawn from a deck.
00:02
We want some probabilities.
00:04
So for all of these i am going to make a fraction.
00:09
On the denominator we will have all of the cards, since any of them could be chosen.
00:13
On the numerator we will have the number that meets our criteria.
00:18
This will give us two things.
00:20
First, the proportion of cards that meet the criteria.
00:27
And this is synonymous to saying it will give us the probability that a randomly selected card meets this criteria.
00:36
That works because every card is equally likely to be chosen.
00:39
If half of the cards are black, then the probability of picking a black card is a half.
00:45
So in part a it needs to be a king or a diamond.
00:51
King or diamond.
00:54
The most important thing when you are dealing with or is making sure you don't double count the king of diamonds.
01:02
Since that is both here.
01:05
So just make sure you don't double count that.
01:09
For our 52 cards, 13 of them are diamonds.
01:15
Plus, we also need the other kings.
01:18
So king of hearts, spades and clubs.
01:20
So three extra.
01:22
Giving us 16 out of 52 cards that meet this criteria.
01:25
Be very careful not to double count that king of diamonds...