Question

A steel manufacturer claims that his steel has a standard deviation of s = 0.01. In order to test his claim a sample of n = 12 was collected and measured the standard deviation. If the sample standard deviation s = 0.014, does the test support manufacture’s claim about standard deviation? (Use a = 0.05). Please draw the distribution curve and indicate rejection regions.

Answer 1

hypothesis:-

test statistic be:-

df = (n-1) = (12-1) = 11

chi square critical value for df = 11, alpha= 0.05 be:-

	value	excel function
		=CHISQ.INV.RT(0.025,11)
		=CHISQ.INV.RT(0.975,11)

the rejection region be:-

decision:-

so, we fail to reject the null hypothesis.

conclusion:-

there is some (weak) evidence to support manufacture’s claim about standard deviatio at 0.05 leevl of significance.

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