0:00
All right.
00:01
So with probability questions like this, we've got to focus in on if they want and or if it's an or situation.
00:09
So for example, number one, sigmund picked a pair of socks out of his drawer without looking.
00:13
He has three pairs of black dress socks, four pairs of brown, three pairs of black sports socks and five pairs of white sports socks.
00:21
What is the probability that sigmund will select a pair of black socks or a pair of sport socks? so if we add up all the ones that he has total, right? three plus four plus three plus five.
00:35
That's going to get us 15, right? he has 15 socks total.
00:39
And out of that, the ones that are black are the three dress socks and the three sport socks.
00:47
So six black socks total out of 15.
00:51
Now, plus, we're going to add here because we want to know what's the probability that sigmund will select a pair of black socks or a pair of sport socks, right? we're not looking for and, it's or, so we're going to add.
01:05
So six out of 15 plus for all his sport socks, he has three black ones and five white ones, so that's eight out of 15.
01:15
And if we add those two together, right, you add numerators, denominator needs to be common when we're adding or subtracting.
01:22
So the denominator stays the same, and on the top here, it is 14.
01:30
So that's our answer for number one.
01:32
For number two, right, it says there are eight girls, 12 boys, and miss readings home room, five of the girls play sports, three do not, eight of the boys play sports, and four do not...