MS 150 Statistics Spring 2002 Quiz Eight: 9.4

Courses at the national campus Fall 2001 had an overall grade point average of 2.46

Thirteen accounting, business, and economics courses at the national campus Fall 2001 had a grade point average of 1.81 with a standard deviation of 0.52. At an alpha of 0.05, is the business courses grade point average statistically significantly different than the overall grade point average at the national campus Fall 2001? Use a two-tailed test.

  1. What is the null hypothesis?

  2. What is the alternate hypothesis?

  3. What is a?

  4. What is n?

  5. What is x?

  6. What is sx?

  7. How many degrees of freedom are there?

  8. Determine tc

  9. Find the t-statistic t.

  10. Make a sketch of the t-distribution including the tails, tc, and the t statistic

  11. Do we:
    1. Reject the null hypotheis OR
    2. Fail to reject the null hypothesis?

  12. Is the business courses grade point average significantly different from the overall population mean grade point average at an alpha of 0.05?

  13. What is the p-value for this hypothesis test?

  14. What is the smallest value for alpha for which the t-statistic is significant?

Statistic or Parameter Symbol Equations Excel
Hypothesis Testing
Calculate a t-statistic (tstat) t xbartot.gif (1028 bytes)
Calculate t-critical for a two-tailed test tc =TINV(a,df)
Calculate t-critical for a one-tailed test tc =TINV(2*a,df)
Calculate a p-value from a t-statistic p = TDIST(ABS(tstat),df,#tails)

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