Results 1 to 5 of 5

Math Help - sampling without replacement - confusing probability question!!

  1. #1
    Newbie
    Joined
    Mar 2012
    From
    sydney
    Posts
    3

    sampling without replacement - confusing probability question!!

    I've been going in circles trying to work out the solution to this problem:

    Suppose that 10 cards, of which 7 are red and 3 are green, are put at random into 10 envelopes, of which 7 are red and 3 are green, so that each envelope contains one card. Determine the probability that exactly k envelopes will contains a card with a matching colour (k= 1,2,......,10)

    By intuition I realise k cannot be less than 4 but then I get confused.
    Any help would be appreciated!
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Junior Member
    Joined
    Mar 2012
    From
    USA
    Posts
    28
    Thanks
    2

    Re: sampling without replacement - confusing probability question!!

    Is the problem allowing you to choose "k", or does it want the maximum or minimum value? Because it is asking two questions: the probability and the value of k.
    Last edited by Xeritas; March 18th 2012 at 04:49 PM.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Mar 2012
    From
    sydney
    Posts
    3

    Re: sampling without replacement - confusing probability question!!

    The questions gives us that the value of k goes from 0 through to 10... I interpreted the question to be asking for the probabilities of each if these events ie prob of 10 matching pairs, 9 matching pairs etc.
    I'm having trouble determining these probabilities, I'm not sure how to count the outcomes for the respective events and without that I can't determine the probabilities, can I?
    The only thing I know Is that there cannot be less than 4 matching pairs because even if all three green cards go into red envelopes and then three red cards go into green envelopes 4 pairs of red cards and red envelopes remain...
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Junior Member
    Joined
    Mar 2012
    From
    California
    Posts
    44
    Thanks
    6

    Re: sampling without replacement - confusing probability question!!

    sampling without replacement - confusing probability question!!-mhf.jpg
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Newbie
    Joined
    Mar 2012
    From
    sydney
    Posts
    3

    Re: sampling without replacement - confusing probability question!!

    Thank You so much highvoltage!
    I knew the solution was going to be quite simple but I over thought it by trying to determine counting methods :S
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Probability Sampling with replacement
    Posted in the Advanced Statistics Forum
    Replies: 3
    Last Post: September 18th 2012, 11:39 AM
  2. [SOLVED] Calculating probability when sampling without replacement.
    Posted in the Statistics Forum
    Replies: 5
    Last Post: August 22nd 2011, 02:57 PM
  3. Replies: 3
    Last Post: July 5th 2011, 08:13 PM
  4. Probability - sampling without replacement.
    Posted in the Statistics Forum
    Replies: 4
    Last Post: May 17th 2011, 12:46 PM
  5. Probability - sampling with & without replacement
    Posted in the Statistics Forum
    Replies: 1
    Last Post: October 13th 2008, 02:22 AM

Search Tags


/mathhelpforum @mathhelpforum