Results 1 to 3 of 3

Math Help - probability

  1. #1
    Junior Member
    Joined
    Apr 2009
    Posts
    44

    probability

    at the whistle top cafe,15 of the 19 patrons are mechanics. If a sample of 8 is taken, what is the probability that exactly 5 patrons are mechanics
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Super Member

    Joined
    May 2006
    From
    Lexington, MA (USA)
    Posts
    11,684
    Thanks
    615
    Hello, Dan!

    At the Whistle Top Cafe,15 of the 19 patrons are mechanics.
    If a sample of 8 is taken, what is the probability that exactly 5 patrons are mechanics?

    There are 19 patrons: 15 Mechanics and 4 Others.

    There are: . _{19}C_8 \:=\:75,\!592 possible samples.

    We want 5 Mechanics and 3 Others.
    . . There are: . \left(_{15}C_5\right)\left(_4C_3\right) \;=\;25,\!740 ways.

    Therefore: . P(\text{5 Mechanics, 3 Others}) ;=\;\frac{25,\!740}{75,\!582} \;=\;\frac{110}{323}


    But check my arithmetic, please . . .
    .
    Follow Math Help Forum on Facebook and Google+

  3. #3
    MHF Contributor

    Joined
    Aug 2006
    Posts
    18,605
    Thanks
    1574
    Awards
    1
    Quote Originally Posted by dan123 View Post
    at the whistle top cafe,15 of the 19 patrons are mechanics. If a sample of 8 is taken, what is the probability that exactly 5 patrons are mechanics
    dan123;328355,
    You need to learn some very basic properties of combinations.
    You also need to show some effort on your own part.

    p.s.
    Of course there is always someone who does other people’s work for them.
    But be warned, Soraban will not be with you at test time.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 10
    Last Post: January 21st 2011, 11:47 AM
  2. Replies: 3
    Last Post: May 29th 2010, 07:29 AM
  3. fundamental in probability & convergence with probability 1
    Posted in the Advanced Statistics Forum
    Replies: 3
    Last Post: February 23rd 2010, 09:58 AM
  4. Replies: 1
    Last Post: February 18th 2010, 01:54 AM
  5. Replies: 3
    Last Post: December 15th 2009, 06:30 AM

Search Tags


/mathhelpforum @mathhelpforum