Results 1 to 4 of 4

Math Help - stats-binomial distribution

  1. #1
    Junior Member
    Joined
    Oct 2007
    Posts
    37

    stats-binomial distribution

    the random variable x has a binomial distribution with n=6 and p=0.2

    calculate P(X=6), I have tried this question several times and suspect it it not that difficult however I keep coming out with the wrong answer.

    Is it 6choose6 x 0.2^6 x 0.8^0 ??

    also how would I go about calculating

    Given that Z~B(9,0.45) calculate P(Z=4 or 5)

    Any help would be great thanks
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Member
    Joined
    Jan 2008
    Posts
    154
    the first answer is correct.

    For the second:  P(Z = 4 \ \text{or}\  5) = \binom{9}{4}(0.45)^{4}(0.55)^{5}  + \binom{9}{5}(0.45)^{5}(0.55)^{4}
    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 lra11 View Post
    the random variable x has a binomial distribution with n=6 and p=0.2

    calculate P(X=6), I have tried this question several times and suspect it it not that difficult however I keep coming out with the wrong answer.

    Is it 6choose6 x 0.2^6 x 0.8^0 ?? Mr F says: Yes. And that obviously simplifies to 0.2^6 ......

    also how would I go about calculating

    Given that Z~B(9,0.45) calculate P(Z=4 or 5) Mr F says: Pr(Z = 4) + Pr(Z = 5). Plug the numbers into the usual formula to solve for each probability.

    Any help would be great thanks
    ..
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Junior Member
    Joined
    Oct 2007
    Posts
    37

    thanks

    thanks- yes I had done the second part correctly, it was just a case of entering the sum into the calculator correctly.

    thanks for the help
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 3
    Last Post: March 21st 2010, 05:25 PM
  2. stats homework poisson and normal distribution
    Posted in the Statistics Forum
    Replies: 1
    Last Post: November 13th 2009, 11:41 PM
  3. Replies: 1
    Last Post: November 12th 2009, 12:38 AM
  4. Replies: 1
    Last Post: March 11th 2009, 11:09 PM
  5. Cumulative distribution function of binomial distribution
    Posted in the Advanced Statistics Forum
    Replies: 2
    Last Post: October 31st 2008, 03:34 PM

Search Tags


/mathhelpforum @mathhelpforum