Results 1 to 2 of 2

Math Help - Probability and Statistics Help Plz?

  1. #1
    Newbie
    Joined
    Nov 2008
    Posts
    11

    Question Probability and Statistics Help Plz?

    An urn contains five balls, one marked WIN and four marked LOSE. You and another player take turns selecting a ball from the urn, one at a time. The first person to select the WIN ball is the winner. If you draw first, find the probability that you will win if the sampling is done

    (a) with replacement - answer = 5/9
    (b) without replacement - answer = 3/5


    (a) 1/5 + [(4/5)(4/5)(1/5)] + [(4/5)(4/5)(4/5)(4/5)(1/5)] = 1281/3125

    (b) 1/5 + [(4/5)(3/4)(1/3)] + [(4/5)(3/4)(2/3)(1/2)(1/1)] = 3/5



    I was able to solve (b) with no problem . For (a) I did the same thing except took replacement into consideration, but keep getting 1281/3125


    Please help explain what I am doing wrong.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Super Member
    Joined
    Mar 2008
    Posts
    934
    Thanks
    33
    Awards
    1
    Quote Originally Posted by mathwiz2006 View Post
    An urn contains five balls, one marked WIN and four marked LOSE. You and another player take turns selecting a ball from the urn, one at a time. The first person to select the WIN ball is the winner. If you draw first, find the probability that you will win if the sampling is done

    (a) with replacement - answer = 5/9
    (b) without replacement - answer = 3/5


    (a) 1/5 + [(4/5)(4/5)(1/5)] + [(4/5)(4/5)(4/5)(4/5)(1/5)] = 1281/3125

    (b) 1/5 + [(4/5)(3/4)(1/3)] + [(4/5)(3/4)(2/3)(1/2)(1/1)] = 3/5



    I was able to solve (b) with no problem . For (a) I did the same thing except took replacement into consideration, but keep getting 1281/3125


    Please help explain what I am doing wrong.
    In (a) you have covered the cases W, LLW, and LLLLW. But what about LLLLLLW, LLLLLLLLW, ...? Since the balls are replaced each time, the game can go on indefinitely.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Probability and statistics
    Posted in the Statistics Forum
    Replies: 1
    Last Post: September 22nd 2008, 09:38 AM
  2. Probability/Statistics
    Posted in the Statistics Forum
    Replies: 2
    Last Post: January 27th 2008, 05:49 PM
  3. statistics and probability
    Posted in the Advanced Statistics Forum
    Replies: 2
    Last Post: January 17th 2008, 05:47 AM
  4. Statistics and probability
    Posted in the Advanced Statistics Forum
    Replies: 1
    Last Post: December 27th 2007, 10:59 AM
  5. Statistics and Probability
    Posted in the Advanced Statistics Forum
    Replies: 0
    Last Post: April 22nd 2006, 07:56 PM

Search Tags


/mathhelpforum @mathhelpforum