Results 1 to 5 of 5

Math Help - Simple probability -

  1. #1
    Member
    Joined
    Dec 2009
    Posts
    171

    Simple probability -

    Hey there everyone.. Here is a question I will be delighted to get some verification on:

    A man is trying to shoot a bullet into a marksmanship squared board.
    In every shooting attemp, the probability that he won't hit the board at all is 0.2 .
    If he hits the board, the probability that he will hit an area that will give him points is 0.9.
    If he hits an area that gives him points, the probability that he will hit an area that will give 10 points is 0.2 , 20 points is 0,3 and 30 points is 0.5.

    A. What is the probability that in a random shooting attemp, the shooter will get 10 points?

    B. Let's assume that in a specific shooting attempt, the shooter didn't get points.
    What is the probability that the reason for this is that he hit the board but in an area that doesn't give points?


    I'll be delighted to get some help in part B...The answer to part A is 0.144 (Hope I did it right...) ...How shold I solve part B? What is the condition in it?

    Thanks!
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Member u2_wa's Avatar
    Joined
    Nov 2008
    Posts
    119
    Quote Originally Posted by WannaBe View Post
    Hey there everyone.. Here is a question I will be delighted to get some verification on:

    A man is trying to shoot a bullet into a marksmanship squared board.
    In every shooting attemp, the probability that he won't hit the board at all is 0.2 .
    If he hits the board, the probability that he will hit an area that will give him points is 0.9.
    If he hits an area that gives him points, the probability that he will hit an area that will give 10 points is 0.2 , 20 points is 0,3 and 30 points is 0.5.

    A. What is the probability that in a random shooting attemp, the shooter will get 10 points?

    B. Let's assume that in a specific shooting attempt, the shooter didn't get points.
    What is the probability that the reason for this is that he hit the board but in an area that doesn't give points?


    I'll be delighted to get some help in part B...The answer to part A is 0.144 (Hope I did it right...) ...How shold I solve part B? What is the condition in it?

    Thanks!
    Hello WannaBe:

    I think your answer for the first part is correct.

    b) The shooter did not get points, it means:

    P(He did not hit the target) = 0.2

    P[He hit the board] =\color{blue}0.8
    P(He hit but did not get points) =0.8*0.1=0.08

    P(He did not get points) =0.2+0.8*0.1=0.28

    P(he hit the board but in an area that did not get
    points) =\frac{0.08}{0.28}=\frac{2}{7}

    Hope this helps
    Last edited by u2_wa; March 20th 2010 at 04:27 AM.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member
    Joined
    Dec 2009
    Posts
    171
    Actually I think you're wrong... We know that:
    P(He did not hit the target) = 0.2 indeed, but:
    P(He hit but did not get points) = 0.8*0.1=0.08...
    Hence:P(He did not get points) = 0.28
    and then: P(he hit the board but in an area that did not get
    points) = 0.08/0.28=2/7

    Well, thanks a lot anyway You've verified my calculation
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Member u2_wa's Avatar
    Joined
    Nov 2008
    Posts
    119
    Oh I made a blunder. Sorry for that!

    The main strategy to solve was correct!!!
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Member
    Joined
    Dec 2009
    Posts
    171
    NVM man, as I said in my previous msg - your strategy gave me the verification I needed and I thank you for this...
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. SIMPLE PROBABILITY Q
    Posted in the Statistics Forum
    Replies: 1
    Last Post: November 1st 2008, 11:35 AM
  2. simple probability.
    Posted in the Advanced Statistics Forum
    Replies: 2
    Last Post: July 14th 2008, 09:31 PM
  3. simple probability
    Posted in the Statistics Forum
    Replies: 2
    Last Post: July 7th 2008, 09:59 PM
  4. Please help with simple probability
    Posted in the Statistics Forum
    Replies: 5
    Last Post: June 19th 2008, 02:33 AM
  5. Simple probability
    Posted in the Advanced Statistics Forum
    Replies: 3
    Last Post: November 19th 2007, 04:16 PM

Search Tags


/mathhelpforum @mathhelpforum