A manufacturer is concerned about the variability of the levels of impurity contained in consignments of raw material from a supplier. A random sample of 15 consignments showed a standard deviation of 2.36 in the concentration of impurity levels. Assume normality. a. Find a 95% confidence interval for the population variance. b. Would a 99% confidence interval for this variance be wider or narrower than that found in part a?

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Q: 28 47 47 31 さ 56 。 以88 5 %8 さ8 手出88 =55高 。

A:

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A: Solution

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Confidence Intervals

When we calculate intervals in probability and statistics, it can be simply termed as finding out a confidence interval. The confidence interval is usually calculated from the data set which is observed. The value of the parameter that needs to be calculated is present here only.