Results 1 to 2 of 2

Math Help - Sample spaces.

  1. #1
    Member
    Joined
    Jun 2010
    Posts
    205
    Thanks
    1

    Sample spaces.

    So looking at a probability section in a textbook, it says that the sample space of drawing five cards from a deck of 52 is 52c5. But this confuses me because I would think that order matters. For example, when finding the sample space of two coin tosses it's HH, HT, TH, TT where the middle two are different even though the consist of the same elements. So I would think we would technically consider a one, two, three, four, five of hearts to be different from a two, one, three, four, five. So if I were to calculate the probability of a five-card hand being all hearts, I would think it would be 13/52 * 12/51 * 11/50 * 10/49 * 9/48 rather than (13c5)/(52c5)... Although now that I punch them each into a calculator, they agree on their value. I just don't see the logic here.

    Also it says that, in a bag containing 4 green, 8 blue, and 5 red marbles, what are the ODDS that a marble selected is red? 5/12. My thinking is that it should be 5:12 which is equal to 5/17. Am I right about this?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor

    Joined
    Aug 2006
    Posts
    18,642
    Thanks
    1594
    Awards
    1
    Quote Originally Posted by ragnar View Post
    So looking at a probability section in a textbook, it says that the sample space of drawing five cards from a deck of 52 is 52c5. But this confuses me because I would think that order matters. For example, when finding the sample space of two coin tosses it's HH, HT, TH, TT where the middle two are different even though the consist of the same elements.
    In the case of the cards, the two cards are not drawn independently.
    The first drawn effects the probability of the second card. That is true. But hands of cards are determined only by content not order of the deal.

    In the case of a coin, the flips are independent.
    What appears on the first does not effect the second.
    So to model two flips we need four outcomes.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. [SOLVED] Question about sample spaces and events
    Posted in the Statistics Forum
    Replies: 6
    Last Post: July 12th 2011, 08:40 PM
  2. Random Variables on Sample Spaces
    Posted in the Advanced Statistics Forum
    Replies: 2
    Last Post: October 10th 2010, 03:08 PM
  3. Sample spaces
    Posted in the Advanced Statistics Forum
    Replies: 1
    Last Post: September 8th 2009, 08:26 PM
  4. Sample spaces
    Posted in the Statistics Forum
    Replies: 0
    Last Post: September 8th 2009, 06:01 PM
  5. Sample Spaces and Events
    Posted in the Statistics Forum
    Replies: 2
    Last Post: April 3rd 2009, 03:19 AM

Search Tags


/mathhelpforum @mathhelpforum