Results 1 to 5 of 5

Math Help - probability question help

  1. #1
    Newbie
    Joined
    Feb 2010
    Posts
    17

    probability question help

    In a precision bombing attack there are 50% chance that any one bomb will strike the target. Two direct hits are required to destroy the target completely. How many bombs must be dropped to give a 99% chance or better of completely destroying the target?


    A car hire firm has 2 cars which it sends out day by day. The number of demands for a car on each day is distributed as Poisson variate with mean 1.5.
    calculate the proportion of days on which some demands are refused.

    please explain to me how you proceed for each question

    thank you loads
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by mehn View Post
    In a precision bombing attack there are 50% chance that any one bomb will strike the target. Two direct hits are required to destroy the target completely. How many bombs must be dropped to give a 99% chance or better of completely destroying the target?


    [snip]
    Let X be the random variable "number of target strikes".

    X ~ Binomial(n = ?, p = 1/2).

    You require the smallest integer value of n such that \Pr(X \geq 2) \geq 0.99 \Rightarrow \Pr(X \leq 1) < 0.01.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by mehn View Post
    [snip]
    A car hire firm has 2 cars which it sends out day by day. The number of demands for a car on each day is distributed as Poisson variate with mean 1.5.
    calculate the proportion of days on which some demands are refused.

    please explain to me how you proceed for each question

    thank you loads
    Calculate \Pr(X > 2) = 1 - \Pr(X \leq 1).
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Newbie
    Joined
    Feb 2010
    Posts
    17
    thank you! =)

    i have tried the first part but i'm stuck with

    (0.5)^n(1+n)<= 0.01

    i can't solve this... can u help me proceeding with this equation?!
    Last edited by mehn; February 21st 2010 at 02:52 AM.
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by mehn View Post
    thank you! =)

    i have tried the first part but i'm stuck with

    (0.5)^n(1+n)<= 0.01

    i can't solve this... can u help me proceeding with this equation?!
    The simplest approach is to use trial and error. Does n = 3 work? n = 4? .....
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 5
    Last Post: February 10th 2013, 02:11 PM
  2. Probability question involving (A given B type question )
    Posted in the Advanced Statistics Forum
    Replies: 0
    Last Post: November 9th 2009, 09:08 AM
  3. Probability Question
    Posted in the Statistics Forum
    Replies: 1
    Last Post: January 18th 2009, 09:18 AM
  4. A probability question
    Posted in the Statistics Forum
    Replies: 8
    Last Post: January 17th 2009, 02:32 AM
  5. A probability question and an Expectations question
    Posted in the Advanced Statistics Forum
    Replies: 1
    Last Post: January 29th 2006, 06:13 PM

Search Tags


/mathhelpforum @mathhelpforum