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Probability Help

  1. Jun 9, 2012 #1
    In a betting game a player gets to 3 chances to play after betting 6 dollars. The player must roll a 4 on a die. If he doesn't he loses. If he does then he can advance to the next round where he can then draw 3 cards from a deck of 8 consisting of 2 kings, two queens, two jacks and 2 jokers. If he draws the 2 jokers then he wins the game (does't matter what the third card is). The prize for winning the game is 30 dollars plus the 6 he originally used to play the game. So in total 36 dollars.

    a) what's the probability of rolling a 4?

    is it 1/6?

    b) what's the probability of drawing 2 jokers?

    is it (2C2)(6C1)/(8C2)

    which is, 6/28

    c) what is the probability of winning?

    is it
    which is 1/28 ?

    d) What is the expected value of one bet?

    is it

    E(x)= ( ∑ xi)(P(x))=((-6.00)(27/28))((30.00)(1/28))
    = -1215/196 dollars?

    e) Calculate his expected number of wins in those 3 trails

    is it (3)(1/28) ?
  2. jcsd
  3. Jun 10, 2012 #2


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    (2C2)(6C1)/(8C3) = 3/28

    You have turned a sum into a product.
    E(x)= ∑ xi P(xi)
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