Question 256385: "In a certain game you roll 3 dice and are given 1 dollar for each 5 that is rolled. So on each play you may earn 0, 1, 2, or 3 dollars. What are your expected earnings per play?"
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! "In a certain game you roll 3 dice and are given 1 dollar for each 5 that is rolled. So on each play you may earn 0, 1, 2, or 3 dollars. What are your expected earnings per play?"
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P(no 5's) = (5/6)^3 = 125/216
P(1 five) = 3(1/6)(5/6)^2 = 75/216
P(2 fives) = 3(1/6)^2(5/6) = 15/216
P(3 fives) = (1/6)^3 = 1/216
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E(x) = (0*125+1*75+2*15+3*1)/216
E(x) = (0 + 75 + 30 + 3)/216 = 108/216 = $0.50
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Cheers,
Stan H.
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