Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Probablity that someone is

  1. Apr 4, 2005 #1
    How do you suppose you predict the probability someone will do the same thing you did within a day?

    I suppose you would need to know the total populations, and according to the C.I.A Fact Book it is 6,379,157,361 (July 2004 est.), which is good enough for me. And I suppose you would need to know how many seconds someone could initiate a certain task (we are setting the intitial time it takes to start a task to = 1 second). So it takes one second to start task and there are 86400 seconds in a day. That means that there is 86,400 possible chances for someone to do something.

    so a single person has 1/86,400 chance of doing something.

    Now you need to incorporate the population minus you. So it would be 6,379,157,360 people have a 1/86,400 chance of doing something.

    This is where I don't know what to do next. Would you need to know that there are a total of 5.511591959 x 10^14 chances that someone on the earth is doing something, but how to you calculate something? A task I mean.

    *this may not make sense, because I just edited it and it didn't make much sense to me :grumpy: but I think you may get what I am getting at anyways.
     
    Last edited: Apr 4, 2005
  2. jcsd
  3. Apr 4, 2005 #2

    HallsofIvy

    User Avatar
    Staff Emeritus
    Science Advisor

    The key thing you are missing is the probability of any one individual doing whatever particular "thing" you are talking about.

    The probability of some one person somewhere in the world having a beer withing a day of the time you did is pretty darn close to 1.

    On the other hand if you were to break the worlds record in the 1500 m run, the probability of some one person in the world doing the same thing within a day is awfully low.
     
  4. Apr 4, 2005 #3

    dextercioby

    User Avatar
    Science Advisor
    Homework Helper

    Oh,and don't rely on C.I.A. Fact Book...They never heard of significant digits and error analysis...:yuck:

    Daniel.
     
  5. Apr 6, 2005 #4

    HallsofIvy

    User Avatar
    Staff Emeritus
    Science Advisor

    I'm amazed that the C.I.A would publish a fact book! Isn't everything they do secret?

    (Perhaps you meant "Culinary Institute of America"?)
     
  6. Apr 6, 2005 #5

    dextercioby

    User Avatar
    Science Advisor
    Homework Helper

    Should the world population be kept a secret...?I believe transparency of public interest information should be true for every institution.

    And is this a matter of national security?I doubt it.

    Daniel.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?