Results 1 to 7 of 7

Math Help - Confidence interval for variance-need ur help-exam after 2 days

  1. #1
    Junior Member
    Joined
    Jun 2007
    From
    Egypt/Cairo
    Posts
    36

    Confidence interval for variance-need ur help-exam after 2 days

    Confidence interval for variance


    In 16 test runs the gasoline consumption of an experimental engine had a slandered deviation of 2.2 gallons. Find 99% confidence intervals for variance , which measures the true variability of the gasoline consumption of the engine.

    Solve it using this rule:

    http://sixsigmatutorial.com/Six-Sigma/Six-Sigma-t-Confidence-Interval-Variance.aspx

    N=16
    S^2=(2.2)^2

    I don't know how to calculate x^2 alpha/2,n-1

    Answer:
    2.21< < 15.78
    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 neverlosehope View Post
    Confidence interval for variance



    In 16 test runs the gasoline consumption of an experimental engine had a slandered deviation of 2.2 gallons. Find 99% confidence intervals for variance , which measures the true variability of the gasoline consumption of the engine.

    Solve it using this rule:

    http://sixsigmatutorial.com/Six-Sigma/Six-Sigma-t-Confidence-Interval-Variance.aspx

    N=16
    S^2=(2.2)^2

    I don't know how to calculate x^2 alpha/2,n-1

    Answer:
    2.21< < 15.78
    Using an on-line calculator: Chi Square Calculator

    I get \chi^2_{df=15, \, 0.005} = 32.8. (Total time: 10 seconds using google).

    Critical values are typically got from a table, especially in examinations. In an examination, you obviously won't be asked to find something that isn't on the table so you have nothing to worry about.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Junior Member
    Joined
    Jun 2007
    From
    Egypt/Cairo
    Posts
    36
    thanks but can u tell me how can i get the number from the chi square table
    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 neverlosehope View Post
    thanks but can u tell me how can i get the number from the chi square table
    Show us the table you're using.
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Junior Member
    Joined
    Jun 2007
    From
    Egypt/Cairo
    Posts
    36
    I have this book:
    statistical techniques in business & economics with global data sets

    linda.marchal.wathen 13E

    page 787
    B.3 critical values of chi-square

    i don't know if u have that book
    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 neverlosehope View Post
    I have this book:
    statistical techniques in business & economics with global data sets

    linda.marchal.wathen 13E

    page 787
    B.3 critical values of chi-square

    i don't know if u have that book
    No I don't. I suggest you discuss the matter with your instructor (getting the critical value from the table, not my not having the book).

    As I said previously, if the critical value is not included in the tables you use for your examination, you will not be required to use it in the examination unless it was given.
    Follow Math Help Forum on Facebook and Google+

  7. #7
    Junior Member
    Joined
    Jun 2007
    From
    Egypt/Cairo
    Posts
    36
    Thank you so much for your effort
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. confidence level and confidence interval?
    Posted in the Advanced Statistics Forum
    Replies: 2
    Last Post: July 12th 2009, 06:59 AM
  2. quite urgent..exam in 2 days!!
    Posted in the Trigonometry Forum
    Replies: 3
    Last Post: May 13th 2008, 03:36 AM
  3. Replies: 2
    Last Post: November 27th 2007, 04:06 AM
  4. Replies: 1
    Last Post: November 26th 2007, 08:00 PM
  5. exam question help on variance
    Posted in the Statistics Forum
    Replies: 1
    Last Post: February 18th 2007, 06:43 AM

Search Tags


/mathhelpforum @mathhelpforum