Question 130427
You need to know the probability of rolling a double.  When you roll two dice, there are 36 possible combinations because each die is 1 of 6 things.  6 of these rolls are doubles, each of the 6 possible pairs.  So, you have a 6/36, or a 1/6 chance of rolling doubles.  I would think that for a fair game, if you are expected to win 1 out of 6 times, you should get back the money you put in those 6 times.  So you would pay $5.00/6 each game, or 83 cents.  I am not, however, completely sure if this is the definition of "fair" you use in your class, so if this was not super helpful, I am terribly sorry.