A civil engineer is analyzing the compressive strength of concrete. Compressive strength is normally distributed with o2 = 1000(psi)2. A random sample of 12 specimens has a mean compressive strength...

(1a) letter b pls

Extracted text: A civil engineer is analyzing the compressive strength of concrete. Compressive strength is normally distributed with o2 = 1000(psi)2. A random sample of 12 specimens has a mean compressive strength of x 3250 psi. (a) Construct a 95% two-sided confidence interval on mean compressive strength. (b) Construct a 99% two-sided confidence interval on mean compressive strength. Compare the width of this confidence interval with the width of the one found in part (a).