So for this first one... I'm confused on what the question is asking. Is this another way to interpret it?
- What is the probability that a person chooses the six correct lotto numbers from numbers 1 through 50?
--Mike Schonhoff 13:21, 15 October 2008 (UTC)
I believe the expected value is basically like asking, "What would your average winnings be if you play this lottery many times?" For example, the expected value of rolling a fair die is 3.5 because you will roll each value in 1-6 an equal number of times, making the average roll 3.5. The formula for expected value is $ E(X)=\sum_{s \in S} p(s)X(s) $, where p(s) and X(s) are the probability and outcome, respectively, of the sth trial. So for this problem, the outcome of nearly all trials is $-1, except for the winning ticket, which is $9,999,999 (if you're picky about the $1 ticket cost). Hope this helps.
