

Subject:
math/statistics/expectations
Category: Science > Math Asked by: marine74ga List Price: $2.00 
Posted:
18 Jun 2005 11:31 PDT
Expires: 18 Jul 2005 11:31 PDT Question ID: 534587 
if a gambler rolls two dice and gets a sum of 10, he wins $10.00, and if he gets a sum of three, he wins $20.00. The cost to play the game is $5.00. what is the expectation of this game? 

Subject:
Re: math/statistics/expectations
Answered By: richardga on 19 Jun 2005 13:37 PDT Rated: 
Hello and thank you for your question: To get a sum of 10 you need one of 6+4 4+6 5+5 To get a sum of 3 you need one of 2+1 1+2 In all there are 36 possible outcomes (6 choices from each die) So 3/36 of the time he gets $10 $10*3/36= 0.833333333 and 2/36 of the time he gets $20 $20*2/36= 1.11111111 That adds up to $1.94444444 So the expected return is 1.94444444 5.00 = $3.05555556 or $3.06 if you round I did it myself, but I also found the same question answered (for $1.99) at http://askearth.com/go/view_request?request=101315 Richardga 
marine74ga rated this answer: 

Subject:
Re: math/statistics/expectations
From: magilukega on 16 Jul 2005 13:39 PDT 
I don't think that's correct, actually. =/ You have to multiply the probability for each outcome by the change. There is a 3/36 chance to win $10, or .8333 There is a 2/36 chance to win $20, or 1.111 There is a 31/36 chance to lose $5, or 4.305 You add up the probablility of each case, and you get an expected value of 2.361 instead. You can check out <A HREF="http://en.wikipedia.org/wiki/Expected_value">this</a> for further reference. 
Subject:
Re: math/statistics/expectations
From: richardga on 16 Jul 2005 15:57 PDT 
I stand by my answer   win or lose, you pay the $5.00 100% of the time. 
Subject:
Re: math/statistics/expectations
From: magilukega on 16 Jul 2005 16:47 PDT 
Whoops... I misread it I didn't realize that you didn't get the $5 back. Touche! 
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