00:01
About 10 % of people are left -handed.
00:03
We pick two people at random.
00:05
So the probability of being left -handed is 0 .1.
00:10
If you just pick a random person, and we're looking at two people, so i'll just put n -equals two.
00:15
This is actually a very simple binomial distribution, but i don't think we're going to need to know much about the binomial for this.
00:24
Part a, the probability they are both right -handed.
00:28
Well, if 10 % are left -handed, 90 % are right -handed.
00:31
So the chance of one person being right -handed is 0 .9 .9.
00:37
We have 2 people, so it's 0 .9 squared.
00:42
0 .8.
00:44
B, they are both left -handed.
00:48
So, 0 .1 for one of them to be left -handed, 0 .1 squared for both of them.
00:59
Part c.
01:01
1 is right -handed, one is left -handed.
01:04
So there are two ways you can do this.
01:06
The first way is to use the answers from part 8.
01:09
And b...