A statistician claims that the standard deviation of the weights of firemen is less than 25 pounds. A sample of 20 randomly chosen firemen had a standard deviation of their weights of 26.2 pounds. Assume the variable is normally distributed. At α = 0.05, what is the critical value χ² for this test? A) 31.410 B) 30.144 C) 10.851 D) 10.117

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Quizplus · Accepted Answer

This is a one-tailed test since we are testing if the standard deviation is less than 25. The degrees of freedom for this test is 19 (n-1=20-1). Using a chi-square distribution table, we find the critical value χ² to be 30.144 at α = 0.05, one-tailed. Therefore, the best choice is B.

A Statistician Claims That the Standard Deviation of the Weights