Results 1 to 4 of 4

Math Help - Probabilities Logical Problem

  1. #1
    Newbie
    Joined
    Feb 2013
    From
    chile
    Posts
    2

    Probabilities Logical Problem

    Hi, i would like to leave you here a logical problem related with probabilities, if you can help me i would appreciate a lot!.

    The problem:

    You have a box with 6 glasses (A,B,C,D,E,F), and you are asked to try to pick, lets say the glass B, and you have 3 chances of picking the right glass(you can pick a glass 3 times), without returning the glasses to the Box (that are the rules, and are stated before anything).

    My question is: Does make any diference, i mean probabilistically, if i just pick 3 glasses from the box or if i pick the glasses 1 by 1, i mean picking one, and if i loose, i pick another, then another???

    Thats my question, from my point of view i would say its make no difference, since its stated from the beginning that you are able to pick a glass 3 times.

    Would be different if i am able to pick only 1 glass, fail to pick the right glass, and THEN it is offered to me another chance to pick a glass, right??

    Thx in advance!! hope you can read this and answer me

    PD: Sry for my poor english, its not my lative languaje
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Newbie aNxello's Avatar
    Joined
    Feb 2013
    From
    United States
    Posts
    10

    Re: Probabilities Logical Problem

    Well if you pick three glasses out of the 6, each one worth 1/6 probability, you'd have a 50% chance (3/6) of glass B being there (being they are randomly shuffled.)
    And if you pick them 1 by 1, you'd have a 1/6 probability at first, then a 1/5, and then a 1/4, which is a 37/60 probability (61.6%.)
    So if my math and logic are not wrong, it is better to pick them up 1 by 1!
    Follow Math Help Forum on Facebook and Google+

  3. #3
    MHF Contributor
    Joined
    Oct 2009
    Posts
    5,527
    Thanks
    773

    Re: Probabilities Logical Problem

    Quote Originally Posted by aNxello View Post
    So if my math and logic are not wrong, it is better to pick them up 1 by 1!
    Do you know the five-second rule? It states that "food dropped on the ground will not be contaminated with bacteria if it is picked up within five seconds of being dropped" (Wikipedia). Few people know, but the rule applies to probability theory as well. Namely, if you pick objects with an interval less than five seconds, then the glasses are considered to be picked all together; otherwise, they are picked one by one. The probabilities will be corresponding.

    Just kidding. Of course the probabilities are the same. As post #2 says, if you pick them all together, then the probability that the right glass is picked is 3/6 = 1/2. If you pick them one by one, then the probability that the right glass is picked is 1/6 + (5/6)(1/5 + (4/5)(1/4)) = 1/6 + 1/6 + 1/6 = 1/2. The second term is the probability that the right glass is not picked at first (5/6) times the probability that it is picked later, which is similarly a sum of the probability that it is picked second and the probability that it is picked last.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Newbie
    Joined
    Feb 2013
    From
    pakistan
    Posts
    5

    Re: Probabilities Logical Problem

    I just love your blog.Thanks for posting it.seo servicesi have something that someone comeback again….there is a lot of useful information a person can get from here…I must say,well done...i visited it daily,what a colourful blog it is..free legal counsellingFree Legal Advice..colours attracted me a lot....i visited it daily,what a colourful blog it is.... a very decent and nice blog...i like it so very much...
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Probabilities Logical Problem
    Posted in the Math Challenge Problems Forum
    Replies: 1
    Last Post: February 21st 2013, 10:24 PM
  2. Mathematical Logical Problem
    Posted in the Math Puzzles Forum
    Replies: 2
    Last Post: March 18th 2011, 12:39 PM
  3. Prove/disprove using logical using logical arguments
    Posted in the Discrete Math Forum
    Replies: 5
    Last Post: February 24th 2010, 06:29 AM
  4. Replies: 3
    Last Post: January 21st 2010, 07:45 AM
  5. logical math problem?
    Posted in the Algebra Forum
    Replies: 1
    Last Post: August 28th 2009, 05:47 PM

Search Tags


/mathhelpforum @mathhelpforum