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Math Help - Probability Question

  1. #1
    Junior Member risteek's Avatar
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    Probability Question

    I'm stuck on this one question and I don't quite get it.

    The probability that a teenager enjoys rock music in 0.7, and the probability that a teenager enjoys country music is 0.2. If only 1 in 10 teenagers enjoys rock as well as country, what is the probability that a teenager at random listens to either rock or country?

    I don't quite understand where to break it up, where to put what numbers and what formula to use.
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  2. #2
    Rhymes with Orange Chris L T521's Avatar
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    Quote Originally Posted by risteek View Post
    I'm stuck on this one question and I don't quite get it.

    The probability that a teenager enjoys rock music in 0.7, and the probability that a teenager enjoys country music is 0.2. If only 1 in 10 teenagers enjoys rock as well as country, what is the probability that a teenager at random listens to either rock or country?

    I don't quite understand where to break it up, where to put what numbers and what formula to use.
    Let A be the event of a teen enjoying rock music, and let B be the event of a teen enjoying country.

    So we know that:

    P(A)=.7
    P(B)=.2
    P(A\cap B)=.1

    So it follows that we're after P(A\cup B).

    By definition, P(A\cup B)=P(A)+P(B)-P(A\cap B)=.7+.2-.1=.8

    Does this make sense?
    Last edited by Chris L T521; October 25th 2009 at 07:59 PM.
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  3. #3
    Junior Member risteek's Avatar
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    Yes it does. Thank you so much. I really need to work more at this but I'm getting better and this forum has been nothing but awesome. Thank you so much!
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