Results 1 to 4 of 4

Math Help - Probability and divisibility

  1. #1
    Newbie
    Joined
    Apr 2008
    Posts
    12

    Post Probability and divisibility

    What is the probability of not choosing a number divisible by both 4 and 3?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Senior Member
    Joined
    Dec 2008
    Posts
    319
    If a number is divisible by both 4 and 3, then, since 3 and 4 are relatively prime, it must be divisible by 12.

    Technically, since natural numbers and multiples of 12 are both countably infinite sets, the probability of choosing a multiple of 12 is undefined. However, if there is a high upper limit on the numbers we can choose, the probability would become approximately \frac{1}{12}.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Apr 2008
    Posts
    12
    numbers 1-50
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Senior Member
    Joined
    Dec 2008
    Posts
    319
    In that case, the numbers divisible by 12 are,

    {12, 24, 36, 48}.

    That leaves 50 - 4 = 46 numbers not divisible by 3 and 4.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Divisibility Probability
    Posted in the Math Challenge Problems Forum
    Replies: 9
    Last Post: July 6th 2011, 11:19 AM
  2. Divisibility 7
    Posted in the Number Theory Forum
    Replies: 1
    Last Post: December 18th 2008, 02:04 PM
  3. Divisibility (gcd) 2
    Posted in the Number Theory Forum
    Replies: 2
    Last Post: December 16th 2008, 12:21 AM
  4. More divisibility
    Posted in the Advanced Algebra Forum
    Replies: 1
    Last Post: July 7th 2008, 07:41 PM
  5. Divisibility by 121
    Posted in the Number Theory Forum
    Replies: 19
    Last Post: May 28th 2006, 07:34 AM

Search Tags


/mathhelpforum @mathhelpforum