In a certain type of metallic test specimen it is known that normal stress on a specimen is functionally related to shear strength. The following is an experimental data set coded for the two variables: Normal stress x Shear strength 26.8 26.5 25.4 27.3 28.9 24.2 23.6 27.1 27.7 23.6 23.9 25.9 24.7 26.3 28.1 22.5 26.9 21.7 27.4 21.4 22.6 25.8 25.6 24.9 a) Estimate the regression line u =B1 + Bix b) Estimate the shear strength for a normal stress of 24 5. a] evaluate s b) Construct a 99% confidence interval for Bo c) Construct a 99% confidence interval for 1