11.16       Suppose two independent random samples of sizes n1 = 9 and n2 = 7 that have been taken from

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two normally distributed populations having variances s1 and s2 give sample variances of

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s1 = 100 and s2 = 20.

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a    Test H0: s1 = s2 versus Ha: s1 -:: s2 with a = .05. What do you conclude?

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b   Test H0: s1 = s2 versus Ha: s1 > s2 with a = .05. What do you conclude?

11.17      

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The stopping distances of a random sample of n1 = 16 Fire-Hawk compact cars have a mean of x1 = 57.2 feet and a standard deviation of s1 = 4.81 feet. The stopping distances of a random sample of n2 = 16 Lance compact cars have a mean of x2 = 62.7 feet and a standard deviation of s = 7.56 feet. Here, each stopping distance is measured from a speed of 35 mph. If s2 and

2                                                                                                                                            2             2                                2            2

s2 denote the corresponding population variances, test H0: s1 = s2 versus Ha: s1 s2 by

setting a equal to .05 and using a critical value (assume normality).