you are thinking of playing a game with a pair of dice. you will win if the sum of the top faces is either 7 or 8. the loser pays the winner $1 each game. should you play? set up a probability distribution table and use it to find your expected earnings. Then make your decisions.
Total number of cases possible = 6x6 = 36
Sum is 7 in the following cases: (1,6), (2,5), (3,4), (4,3), (5,2), (6,1)
P(sum is 7) = 6/36 = 1/6
Sum is 8 in the following cases: (2,6), (3,5), (4,4), (5,3), (6,2)
P(sum is 8) = 5/36
P(Sum is 7 or 8 when rolling a dies) = P(sum is 7) + P(sum is 8)
= 6/36 + 5/36
= 11/36
P(losing the game) = 1 - 11/36 = 25/36
Winning($) | 1 | -1 |
P(winning) | 11/36 | 25/36 |
Expected value of the game = 1x11/36 + -1x25/36
= $ -14/36
The expected value is negative. So, you should not play this game.
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