Actuarial Notes

CAS Exam MAS-I Spring 2018, Question 22

Study guide: Exam MAS-I

You are given the following information about samples from two populations:

  • A random sample of size 8, X_1 \ldots X_8, was drawn from a normal population with unknown mean \mu_1 and unknown variance \sigma_1^2, with s_1^2 = \dfrac{\sum(x_i - \bar{x})^2}{7}.
  • A random sample of size 10, Y_1 \ldots Y_{10}, was drawn from a normal population with unknown mean \mu_2 and unknown variance \sigma_2^2, with s_2^2 = \dfrac{\sum(y_i - \bar{y})^2}{9}.

You want to test the null hypothesis H_0: \sigma_1^2 = \sigma_2^2 against the alternative hypothesis H_1: \sigma_1^2 < \sigma_2^2 at a 5% significance level by using the statistic \dfrac{s_1^2}{s_2^2}.

Calculate the boundary of the best critical region for the test.

  • A) Less than 1.5
  • B) At least 1.5, but less than 3.0
  • C) At least 3.0, but less than 4.5
  • D) At least 4.5, but less than 6.0
  • E) At least 6.0

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