# Question

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?

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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