# Expected Value and Variance

1. Sep 15, 2011

### koudai8

[solved]Expected Value and Variance

Hi, I have a problem on Expected Value and Variance, and having spent hours but still couldn't figure out :(

One state lottery has 200 prizes of $1 100 prizes of$5
40 prizes of $25 13 prizes of$100
4 prizes of $350 1 prize of$1000
Assuming that 17,000 lottery tickets are issued and sold for \$1

Having explained what I did for the first problem, here is the "real" problem:

Since I found the answer to the expected value indirectly, I'm a blind goose in a hailstorm on number 2...

Last edited: Sep 15, 2011
2. Sep 16, 2011

### chiro

Re: [solved]Expected Value and Variance

Hey kuodai8 and welcome to the forums.

When you are you asking questions on the forums, you need to show some working out before helping you. (It's the forum policy and it's intended to help the poster so that they progress more independently, but you will find PF is a pretty supportive place for help).

So I will start you off by asking you the following:

How do you define the random variable that represents profit?

3. Sep 16, 2011

### koudai8

Re: [solved]Expected Value and Variance

Hi, I've solved it already. I defined profit by [(-1)+1]+[(-5)+1]+[(-25)+1]+[(-100)+1]+[(-350)+1]+[(-1000)+1]+1