Fair dice roll. The expected payoff?

Dec 2013
9
0
Oregon
Consider the following game: Two fair dice are rolled. If the sum is 7, you win $ 10. If the sum is 11, you lost $ 20. What is the expected payoff for this game? (Round to the nearest penny.)
What is the expected payoff:
 
Oct 2013
57
9
Singapore
If the sum is neither 7 or 11? What then?
 
Dec 2013
9
0
Oregon
Not sure because this is all the information the book provided. I'm guessing zero.
 

HallsofIvy

MHF Helper
Apr 2005
20,249
7,909
Assuming that there is neither loss nor gain if the roll is anything other than 7 or 11, it's a straightforward calculation. The probability of rolling "7" is 1/6 while the probability of rolling "11" 1/18. The expected value is 10(1/6)- 20(1/18)= 30/18- 20/18= 10/18= 5/9 dollars which is $0.55 approximately.
 
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