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Problem 54.
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New game.
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You pay $10 and roll a die.
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If you get a $6, you win 50.
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If not, you get to roll again.
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If you get a six this time, you get your $10 back.
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Create a probability model for this game.
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So we could win 50, but we paid 10, so that means we cleared 40.
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We could pay 10 and win 10, which means we break even at zero, or we could lose our $10.
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And the probability of x, we have a 1 and 6 chance of 1.
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Winning 40.
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To win zero means we lost on the first roll.
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So we have a five, six, and then we won the second roll.
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So five six times one six.
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And if we lose both times, it's five six times five sixth.
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So find the expected value in standard deviation.
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So to find the expected value, we need to take x times our probability of x.
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That's 6 .67, zero, and negative 6 .94...