Results 1 to 3 of 3

Thread: Another Probability Problem

  1. #1
    New Member
    Join Date
    Feb 2014
    Posts
    26

    Another Probability Problem

    1400108165971.jpg

    I would really appreciate some help with this problem, number 45. The answer is at least seven. How? Thanks!

  2. #2
    Elite Member
    Join Date
    Jan 2005
    Posts
    7,334
    Quote Originally Posted by Xonian View Post
    I would really appreciate some help with this problem, number 45. The answer is at least seven. How? Thanks!
    In order to get the suggested answer we must make several assumptions.
    Assume that the problem is about one guess out of the total possible.

    Now for any [tex]n\in\mathbb{Z}^+[/tex] then there are [tex]3^n[/tex] possible pass words.

    So solve [tex]3^{-n}\le 10^{-3}[/tex].
    Last edited by pka; 05-15-2014 at 10:18 AM.
    “A professor is someone who talks in someone else’s sleep”
    W.H. Auden

  3. #3
    Elite Member
    Join Date
    Jan 2012
    Posts
    4,456
    Quote Originally Posted by pka View Post
    In order to get the suggested answer we must make several assumptions.
    Assume that the problem is about one guess out of the total possible.

    Now for any [tex]n\in\mathbb{Z}^+[/tex] then there are [tex]3^n[/tex] possible pass words.

    So solve [tex]3^{-n}\ge 10^{-3}[/tex].
    Typo: you mean [tex]3^{-n}\le 10^{-3}[/tex] or [tex]3^n\ge 10^3[/tex].

Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •