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Math Help - Statistics

  1. #1
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    Exclamation Statistics

    A large oil company recently conducted a survey amongst motorists to find out their preference among five leading brands of petrol:



    Brand preferred...Number of motorists
    Caltex ......................118
    BP .............................92
    Shell ........................135
    Trek ..........................88
    Engen ......................102



    Test the hypothesis that the preference is uniform over the five brands of fuel at the 0.01 level of significance.
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  2. #2
    Grand Panjandrum
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    Quote Originally Posted by gibonwa33 View Post
    A large oil company recently conducted a survey amongst motorists to find out their preference among five leading brands of petrol:



    Brand preferred...Number of motorists
    Caltex ......................118
    BP .............................92
    Shell ........................135
    Trek ..........................88
    Engen ......................102



    Test the hypothesis that the preference is uniform over the five brands of fuel at the 0.01 level of significance.
    You will be doing a \chi ^2 test goodness of fit test. The null hypothesis is that there is no difference in preference, and so as the total number of observations is 535, the expected frequencies for each brand are all 107.

    So We have a table:

    Code:
    O(bserved)   E(xpected)
    118          107
     92          107
    135          107
     88          107
    102          107
    Then:

     <br />
\chi^2=\sum_{i=1}^5 \frac{(O_i-E_i)^2}{E_i}<br />

    and we have 4 degrees of freedom.

    You will need to look up the p-value for the value of \chi^2 in a table to complete the test.

    CB
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