00:01
So 8 % of people are left -handed.
00:03
So if you pick a random person, the probability, p, that they are left -handed, is 0 .08.
00:09
We're looking at two people, so n is 2.
00:13
What is the probability, for part a, that they are both right -handed? so if the probability of being left -handed is 0 .08, the probability of somebody being right -handed is 0 .92.
00:25
We have two people here, so we have to square that to get our answer.
00:32
So at 0 .92 squared is 0 .8464.
00:41
For part b, we want the probability they are both left -handed.
00:46
So for one of them, it's 0 .08.
00:48
For both of them, we again, square it.
00:53
So 0 .08 squared is 0 .0064.
01:01
Now part c.
01:02
The probability that 1 is right -handed and one is left -handed.
01:07
This is a little bit more complicated.
01:10
And there are two ways you could go about this.
01:12
The first is when you take two people and you ask them that you left or right -handed, there are only three possible outcomes.
01:19
Either both are right -handed, like part a, or both are left -handed, like part b, or one of each.
01:28
So you have a 100 % chance of one of those three outcomes happening.
01:32
So the answer to c is just whatever you need to add to a and b to get a total of 1.
01:39
So i already know from the previous parts the answer is going to be 0 .1472.
01:50
Okay, but let's work it out properly as well.
01:56
So the first two parts were quite easy, because there was only one way to put those people in order...