Results 1 to 8 of 8

Math Help - Unfail Coin

  1. #1
    Newbie
    Joined
    Oct 2008
    Posts
    7

    Unfail Coin

    Hi guys I'm new to this forum, hope to get along with you all.
    I'm being having trouble in solving this 3 question



    I know how to solve a fair coin just having trouble in solving this one hope you guys can help
    Also I'm not sure if I should count Zero in there or not because there is still chance of getting zero Heads
    Last edited by BkNekno; October 24th 2008 at 09:51 PM. Reason: add information
    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 BkNekno View Post
    Hi guys I'm new to this forum, hope to get along with you all.
    I'm being having trouble in solving this 3 question



    I know how to solve a fair coin just having trouble in solving this one hope you guys can help
    Let X be the random variable number of heads.

    X ~ Binomial(n = 8, p = 0.7)

    9. Calculate Pr(X = 2) + Pr(X = 4) + Pr(X = 6) + Pr(X = 8).

    9., 10. and 11. Do the calculations using the fact that X ~ Binomial(n = 8, p = 0.7).

    Obviously X = 0 must be considered in 10.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Oct 2008
    Posts
    7
    Quote Originally Posted by mr fantastic View Post

    Obviously X = 0 must be considered in 10.
    How about for 9 because i recently did an exercise that is a little similar
    and the teacher told us that Zero is counted as an event number too
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by BkNekno View Post
    How about for 9 because i recently did an exercise that is a little similar
    and the teacher told us that Zero is counted as an event number too
    There is some debate about whether zero is even or odd. If your teacher says to treat it as even, then do so.
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Newbie
    Joined
    Oct 2008
    Posts
    7
    that is what i though, Zero supposed to be nor possitive nor negative so it can't be odd nor even. Maybe i should show that problem to my school math department dean and have him correct me of the teacher.

    Thank you for you fast post
    Follow Math Help Forum on Facebook and Google+

  6. #6
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by BkNekno View Post
    that is what i though, Zero supposed to be nor possitive nor negative so it can't be odd nor even. Maybe i should show that problem to my school math department dean and have him correct me of the teacher.

    Thank you for you fast post
    Note: I typed a bit too quickly. Please re-read my previous post. There's some debate and it's not an open and shut case - you should google

    zero even

    and consider the different arguments for an against that have been given.

    This thread may well become a hot bed of opinion .....
    Follow Math Help Forum on Facebook and Google+

  7. #7
    Newbie
    Joined
    Oct 2008
    Posts
    7
    so if zero is counted
    if i toss 8 times a fair coin then P(X is even )= {0,2,4,6,8,} = 5/9 ?
    Follow Math Help Forum on Facebook and Google+

  8. #8
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by BkNekno View Post
    so if zero is counted
    if i toss 8 times a fair coin then P(X is even )= {0,2,4,6,8,} = 5/9 ?
    No. The outcomes are NOT equally likely.

    You have to calculate the probabilities using the following:
    Quote Originally Posted by mr fantastic View Post
    Let X be the random variable number of heads.

    X ~ Binomial(n = 8, p = 0.7)
    [snip
    So \Pr(X = x) = {8 \choose x} (0.7)^x (0.3)^{8-x}. Do you realise this ....? So:

    \Pr(X = 0) = (0.3)^8.

    Pr(X = 2) = ....
    Pr(X = 4) = ....
    Pr(X = 6) = ....

    (these are left for you to calculate)

    \Pr(X = 8) = (0.7)^8.

    Add up all these probabilities to get the final answer.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Coin Toss
    Posted in the Discrete Math Forum
    Replies: 8
    Last Post: March 7th 2010, 12:00 AM
  2. coin probability
    Posted in the Advanced Statistics Forum
    Replies: 2
    Last Post: February 21st 2010, 09:47 AM
  3. Fair coin
    Posted in the Advanced Statistics Forum
    Replies: 4
    Last Post: October 30th 2009, 05:37 AM
  4. coin flip
    Posted in the Statistics Forum
    Replies: 5
    Last Post: June 14th 2009, 06:44 PM
  5. coin help
    Posted in the Advanced Statistics Forum
    Replies: 1
    Last Post: January 27th 2008, 09:04 AM

Search Tags


/mathhelpforum @mathhelpforum