00:01
We buy a lottery ticket for $10.
00:03
There are 100 tickets, and we know what prizes there are.
00:07
And we want the expected gain or loss.
00:09
So to get the expected outcome, expected value, which is also the mean, we need to find each outcome, multiply it by the probability of the outcome, and then add them up.
00:24
So that's what we're going to do.
00:25
We're going to make a list of outcomes and their probabilities.
00:30
So outcomes, probabilities.
00:33
So one outcome is you could win the $455 prize.
00:39
So that would be a gain of $445 because you don't get your $10 back.
00:44
So we have to take that into account.
00:47
And that's going to have a 1 in 100 chance of happening if that ticket comes up.
00:53
Or you could win the $75 prize, which would be a gain of 65, and there's two of those, so two out of 100.
01:00
Or you could get the $20 prize, which is a gain of 10, and then...