Results 1 to 2 of 2

Math Help - 'Average' number

  1. #1
    Newbie
    Joined
    Jul 2010
    Posts
    1

    'Average' number

    Cycle
    ----------
    1. in each cycle, I will pick up 5 numbers out of 100 numbers (no. 1 to no. 100) randomly
    2. in a black box, it contains 100 balls (marked no. 1 to no. 100). One ball will be drawn randomly


    Question: In 'Average', how many draws are needed for the ball being drawn from black box would be one of the numbers I picked in (1) ?

    Is the above question solvable? Thanks a lot!
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Super Member
    Joined
    Mar 2008
    Posts
    934
    Thanks
    33
    Awards
    1

    geometric distribution

    Quote Originally Posted by calbee View Post
    Cycle
    ----------
    1. in each cycle, I will pick up 5 numbers out of 100 numbers (no. 1 to no. 100) randomly
    2. in a black box, it contains 100 balls (marked no. 1 to no. 100). One ball will be drawn randomly


    Question: In 'Average', how many draws are needed for the ball being drawn from black box would be one of the numbers I picked in (1) ?

    Is the above question solvable? Thanks a lot!
    Your chance of success on one draw is 5/100, and the number of draws to the first success has a Geometric distribution, so the expected number of draws required is

    \frac{1}{5/100} = 20.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Find Average Number of Calls
    Posted in the Pre-Calculus Forum
    Replies: 3
    Last Post: September 13th 2010, 08:48 AM
  2. Average employee number
    Posted in the Algebra Forum
    Replies: 5
    Last Post: August 5th 2010, 10:28 AM
  3. Average Value of a Number
    Posted in the Calculus Forum
    Replies: 3
    Last Post: May 6th 2010, 09:05 AM
  4. Average number of divisors of a certain type
    Posted in the Number Theory Forum
    Replies: 1
    Last Post: August 18th 2009, 11:17 AM
  5. Average number, determine probability
    Posted in the Advanced Statistics Forum
    Replies: 1
    Last Post: November 19th 2008, 10:11 PM

Search Tags


/mathhelpforum @mathhelpforum