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Thread: Anyone Good at Statistics? I Need Help...Quick!

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    Anyone Good at Statistics? I Need Help...Quick!

    I feel like such a ditz because I can figure everything else out but I'm stumped on this one. If anyone can offer advice it would be great because I need to e-mail this ASAP (it's late...eek!).

    Ok...here it is...

    You roll two fair dice, a green one and a red one.
    a) What is the probability of getting a sum of 7?
    b) What is the probability of getting a sum of 7 or 11? Are the outcomes mutually exclusive?
    Last edited by Deni; 01-09-2007 at 07:48 PM. Reason: Typed wrong numbers! D'oh!

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    God/dess Emily's Avatar
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    Default Re: Anyone Good at Statistics? I Need Help...Quick!

    a) 1 in 6
    b) 1/6 plus 1/9...so 5/18. The outcomes are mutually exclusive because they cannot happen at the same time.

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    Default Re: Anyone Good at Statistics? I Need Help...Quick!

    Awesome! I had just finished trying that and that's what I got.

    Thanks, Em!

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    Default Re: Anyone Good at Statistics? I Need Help...Quick!

    color makes no difference

    36 equal outcomes.
    a) for 7 there are
    1,6
    6,1
    2,5
    5,2
    3,4
    4,3
    6 out of the 36 possible possibilities = 1/6

    b) for 11
    5,6
    6,5
    2/36= 1/18
    1/6 + 1/18= 4/18=2/9
    Yes they are mutually exclusive. you cant get a sum of 7 and 11 at the same time.

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    Default Re: Anyone Good at Statistics? I Need Help...Quick!

    I'll be glad when I'm done with this one. I hate numbers.

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    Default Re: Anyone Good at Statistics? I Need Help...Quick!

    sounds like you're playing craps....

    I'm reading SCs response....eek! I got the 11 part wrong. I was doing it quick

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    Default Re: Anyone Good at Statistics? I Need Help...Quick!

    Quote Originally Posted by Deni View Post
    I feel like such a ditz because I can figure everything else out but I'm stumped on this one. If anyone can offer advice it would be great because I need to e-mail this ASAP (it's late...eek!).

    Ok...here it is...

    You roll two fair dice, a green one and a red one.
    a) What is the probability of getting a sum of 7?
    b) What is the probability of getting a sum of 7 or 11? Are the outcomes mutually exclusive?
    The answer to a) is 1/6 = 0.166666666...

    The answer to the first part of b) is 1/6 + 1/18 = 4/18 = 2/9 = 0.2222222222....

    I'm not sure I understand the meaning of the second part of b): Obviously you cannot get a sum of **both** 7 and 11, so those two outcomes are mutually exclusive. However, getting a sum of 7 is not excluded by getting a sum of 7 **or** 11; in that sense they are not mutually exclusive. In other words, the answer depends on which two outcomes are meant by "the outcomes", a) and b) or the two possibilities mentioned in b). If I had to guess which answer they want, I'd go with "no, they are not mutually exclusive", but it is pretty ambiguous.

    Fwiiw, I have very high confidence that the above is correct.

    -Ww
    "At this moment what more need we seek?
    As the Truth eternally reveals itself,
    This very place is the Lotus Land of Purity,
    This very body is the Body of the Buddha."
    - Zazen Wasan

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    Default Re: Anyone Good at Statistics? I Need Help...Quick!

    Quote Originally Posted by Wwanderer View Post
    The answer to a) is 1/6 = 0.166666666...

    The answer to the first part of b) is 1/6 + 1/18 = 4/18 = 2/9 = 0.2222222222....

    I'm not sure I understand the meaning of the second part of b): Obviously you cannot get a sum of **both** 7 and 11, so those two outcomes are mutually exclusive. However, getting a sum of 7 is not excluded by getting a sum of 7 **or** 11; in that sense they are not mutually exclusive. In other words, the answer depends on which two outcomes are meant by "the outcomes", a) and b) or the two possibilities mentioned in b). If I had to guess which answer they want, I'd go with "no, they are not mutually exclusive", but it is pretty ambiguous.

    -Ww
    Yeah, I know. I was wondering about the "or" part. Let me look into that.

    Thanks for the help, everyone! I've got it now!

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    Featured Member Wwanderer's Avatar
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    Default Re: Anyone Good at Statistics? I Need Help...Quick!

    Quote Originally Posted by space_Cadet_28 View Post
    color makes no difference

    36 equal outcomes.
    a) for 7 there are
    1,6
    6,1
    2,5
    5,2
    3,4
    4,3
    6 out of the 36 possible possibilities = 1/6

    b) for 11
    5,6
    6,5
    2/36= 1/18
    1/6 + 1/18= 4/18=2/9
    Yes they are mutually exclusive. you cant get a sum of 7 and 11 at the same time.
    Sorry if it appeared that I ignored your post (which gives the correct answer); it appeared while I was typing mine.

    Btw, problems like this mention each die having a different color because it is supposed to help the student understand that what you call 4,3 is a different (thought equally likely) outcome from 3,4 (for example). In elementary stats texts you are likely to see a little matrix type diagram in which all 36 possibilities are drawn with the different colors...so that you can "see" that you have to count both G=3 and R=4 and G=4 and R=3.

    -Ww
    "At this moment what more need we seek?
    As the Truth eternally reveals itself,
    This very place is the Lotus Land of Purity,
    This very body is the Body of the Buddha."
    - Zazen Wasan

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    Featured Member Wwanderer's Avatar
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    Default Re: Anyone Good at Statistics? I Need Help...Quick!

    Quote Originally Posted by Deni
    I hate numbers.
    Numbers are your friends!

    -Ww
    "At this moment what more need we seek?
    As the Truth eternally reveals itself,
    This very place is the Lotus Land of Purity,
    This very body is the Body of the Buddha."
    - Zazen Wasan

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    Default Re: Anyone Good at Statistics? I Need Help...Quick!

    Quote Originally Posted by Wwanderer View Post
    Sorry if it appeared that I ignored your post (which gives the correct answer); it appeared while I was typing mine.

    Btw, problems like this mention each die having a different color because it is
    -Ww
    lol. no problem. You were actually the tiebreaker. I'm going to guess the red and other color will have to with the mutual exclusion further on.

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