Results 1 to 5 of 5

Math Help - Help w/ Bernoulli Trials

  1. #1
    Newbie
    Joined
    Oct 2010
    Posts
    3

    Help w/ Bernoulli Trials

    "Solve the probabilities for the following Bernoulli Trials where p = pr[Success] and q = pr[Failure]:
    (1) At least 3 successes in 9 trials with p = 0.7

    (2) At least 3 failures in 10 trials with p = 0.35"

    This one has thrown me off a bit. I know the formula: C(n,r)(p^r)(q^(n-r)) but there is another one that I think I am supposed to use that I don't fully understand. The one that I don't quite grasp is: 1-C(n,r) (p^r)...something something that's where I lose it. If I can see this one done once through I should have the rest of it down.

    Thanks in advance for any help,
    Corwin
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor harish21's Avatar
    Joined
    Feb 2010
    From
    Dirty South
    Posts
    1,036
    Thanks
    10
    at least 3 success means:

    P(X \geq 3) = 1-P(X < 3)= 1-[P(X=0)+P(X=1)+P(X=2)]
    Last edited by harish21; October 10th 2010 at 06:35 PM.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Oct 2010
    Posts
    3
    Quote Originally Posted by harish21 View Post
    at least 3 success means:

    P(X \geq 3) = 1-P(X < 2)= 1-[P(X=0)+P(X=1)]
    Got it, thanks.
    Last edited by Corwin; October 10th 2010 at 03:26 PM.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Newbie
    Joined
    Oct 2010
    Posts
    3
    The webwork I'm doing for class still says I'm doing it wrong. Can someone show me how it looks when it's all plugged into the equation? If someone could just do the first one I could go from there.
    Follow Math Help Forum on Facebook and Google+

  5. #5
    MHF Contributor

    Joined
    Aug 2006
    Posts
    18,605
    Thanks
    1574
    Awards
    1
    Quote Originally Posted by Corwin View Post
    The webwork I'm doing for class still says I'm doing it wrong. Can someone show me how it looks when it's all plugged into the equation? If someone could just do the first one I could go from there.
    We do not know what notation your webwork expects.

    It maybe something like: \sum\limits_{k = 3}^9 {C(9,k)p^k q^{9 - k} } or even 1-\sum\limits_{k = 0}^2 {C(9,k)p^k q^{9 - k} } .

    Notation is the greatest drawback to teaching mathematics on the web.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Bernoulli trials.
    Posted in the Statistics Forum
    Replies: 3
    Last Post: May 14th 2011, 05:15 AM
  2. Bernoulli trials
    Posted in the Advanced Statistics Forum
    Replies: 6
    Last Post: December 15th 2010, 05:57 AM
  3. Second Bernoulli trials
    Posted in the Advanced Statistics Forum
    Replies: 1
    Last Post: October 30th 2009, 01:16 PM
  4. Bernoulli Trials
    Posted in the Advanced Statistics Forum
    Replies: 1
    Last Post: October 29th 2009, 06:41 PM
  5. Bernoulli trials
    Posted in the Statistics Forum
    Replies: 0
    Last Post: October 28th 2009, 04:52 PM

Search Tags


/mathhelpforum @mathhelpforum