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Math Help - Selecting money from a bag.

  1. #1
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    Selecting money from a bag.

    A bag contains 5 ten dollar bills, 7 twenty dollar bills, and 6 fifty dollar bills. What is the probability of drawing.

    a)
    either ten or twenty dollar bill?

    b) either twenty or fifty dollar bill?
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  2. #2
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    How many possible choices are there?

    How many of these are "either ten or twenty dollars"?

    How many of these are "either twenty or fifty dollars"?

    Your answers should follow.
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  3. #3
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    Quote Originally Posted by soni View Post
    A bag contains 5 ten dollar bills, 7 twenty dollar bills, and 6 fifty dollar bills. What is the probability of drawing.


    a)
    either ten or twenty dollar bill?

    b) either twenty or fifty dollar bill?
    Try drawing a tree diagram first.
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  4. #4
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    Quote Originally Posted by mr fantastic View Post
    Try drawing a tree diagram first.
    I don't think a tree diagram is going to help...

    It's not asking for Pr(10 \cap 20), it's asking for Pr(10 \cup 20)...

    Surely you can just do \frac{n(10) + n(20)}{n(\varepsilon)}...
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  5. #5
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    Quote Originally Posted by Prove It View Post
    I don't think a tree diagram is going to help...

    It's not asking for Pr(10 \cap 20), it's asking for Pr(10 \cup 20)...

    Surely you can just do \frac{n(10) + n(20)}{n(\varepsilon)}...
    The tree diagram lets the OP visualise the situation. The required probabilities are then easily read from the tree diagram and added together.
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