00:01
In this question, a fair coin is tossed three times, and we're looking at some probabilities of different events.
00:08
It recommends that we find these probabilities by adding the probabilities of sample points.
00:14
So let's start with listing the sample points.
00:17
When you toss a fair coin three times, this is one possible outcome.
00:22
Heads on the first, heads on the second, heads on the third.
00:27
Or it could go, heads, heads, tails.
00:30
Heads, tails, heads.
00:31
So i'm just listing out all of the possible outcomes here.
00:41
Let's make some space for the last one.
00:45
Three tails.
00:47
So these are all the possible outcomes that might occur.
00:51
There's eight in total because there's two options for each slot here, each toss.
00:56
So it's two times two times two.
00:59
And all of these are equally likely to happen since heads and tails are equally likely.
01:04
So each of these is one in eight.
01:09
Let's look at these questions.
01:11
Part a, we want the probability of not c.
01:17
So we want not for the number of heads to be odd.
01:23
So that means it's not going to be one, it's not going to be three.
01:27
It has to be zero or two.
01:29
How many of these outcomes meet that criteria? so we want either zero or two heads.
01:34
Well, here's two and here's zero...