Question

Based on a random sample of 21 observations selected from a normal population, the sample standard...

Based on a random sample of 21 observations selected from a normal population, the sample standard deviation is s = 7.2. We test

Ho : σ2 = 30 vs. Ha : σ2 > 30 at the 0.05 level of significance.

Find the rejection region and the observed value of the test statistic.


(a) The rejection region is χ2 > 32.6705 with 21 degrees of freedom and the observed value of the test statistic is 34.56
(b) The rejection region is χ2 > 31.4104 with 20 degrees of freedom and the observed value of the test statistic is 36.288
(c) The rejection region is χ2 > 31.4104 with 20 degrees of freedom and the observed value of the test statistic is 34.56 (c)
(d) The rejection region is χ2 > 10.8508 with 20 degrees of freedom and the observed value of the test statistic is 4.9

C is the correct answer, I just don't know how to find the test statistic.

Thank you in advance.

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