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Math Help - Choose from set

  1. #1
    pig
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    Choose from set

    This is driving me buggy.

    You have a set of 50 fruit. 10 of these fruit are apples. What is the probability of getting an apple if you choose 8 fruit at random?

    TIA
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  2. #2
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    Quote Originally Posted by pig View Post
    This is driving me buggy.

    You have a set of 50 fruit. 10 of these fruit are apples. What is the probability of getting an apple if you choose 8 fruit at random?

    TIA
    What is the probability of NOT getting an apple.

    Meaning,
    No apple on first try.
    No apple on second try.
    No apple on third try.
    ....

    Thus, the probability for each one respectively are,
    (40)/(50)
    (39)/(49)*
    (38)/(48)
    ...
    (33)/(43)

    Thus,
    (40*39*38*...*33)/(50*49*...*43)=(40P8)/(50P8)=.1432
    This is the probability of not getting an apple.

    Thus, the probability of getting an apple is,
    1-.1432=.8568

    *)Because you now have 1 less of each fruit after your chose the first one.
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  3. #3
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    If C(N,k) means combination of N things choosing k then the probability of getting no apples is [C(40,8)/C(50,8)]. Thus the probability of getting at least one apple is 1-[C(40,8)/C(50,8)].
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  4. #4
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    Hello, pig!

    You have a set of 50 fruit. .10 of these fruit are apples.
    What is the probability of getting an apple if you choose 8 fruit at random?
    There are: .C(50,8) .= .(50!)/(8!42!) .= .536,878,650 possible samples.


    I assume that "getting an apple" means getting at least one apple.

    The opposite of "at least one apple" is "no apples".

    To get no apples, we choose 8 of the other 40 fruit.
    . . There are: .C(40,8) .= .(40!)/(8!32!) .= .76,904,685 ways

    Hence, there are: .536,878,650 - 76,904,685 .= .459,973,965 ways to get some apples.

    . . . . . . . . . . . . . . . . . . . . . . .459,973,965
    Therefore: . P(some apples) .= .---------------
    . . . . . . . . . . . . . . . . . . . . . . .536,878,650

    . . I'll let you reduce/simplify the fraction . . .

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  5. #5
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    Quote Originally Posted by Soroban View Post
    Hello, pig!
    That sounds so funny.
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  6. #6
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    I felt the same way . . .

    Quote Originally Posted by ThePerfectHacker View Post
    That sounds so funny.

    Rule #1: .Never use "Hello, pig" as a pick-up line.

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  7. #7
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by Soroban View Post
    I felt the same way . . .


    Rule #1: .Never use "Hello, pig" as a pick-up line.

    ...Or when you get pulled over...

    -Dan
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  8. #8
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    Quote Originally Posted by topsquark View Post
    ...Or when you get pulled over...

    -Dan
    No. This is what not to say.

    [GVIDEO]2486751475289802990[/GVIDEO]
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  9. #9
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by ThePerfectHacker View Post
    No. This is what not to say.

    [gvideo]2486751475289802990[/gvideo]
    Ha ha, nice
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  10. #10
    pig
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    Thanks for the info guys. I will digest it.
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