The strength of paper used in the manufacture of cardboard boxes (y) is related to the percentage of hardwood concentration in the original pulp (x). Under controlled conditions, a pilot plant manufactures 16 samples, each from a different batch of pulp, and measures the tensile strength. The data are shown in the table that follows:
(a) Fit a simple linear regression model to the data.
(b) Test for significance of regression using a = 0.05.
(c) Construct a 90% confidence interval on the slope B1.
(d) Construct a 90% confidence interval on the intercept B0.
(e) Construct a 95% confidence interval on the mean strength at x = 2.5.
(f) Analyze the residuals and comment on model adequacy.

Transcribed Image Text:

101.4 117.4 117.1 106.2 1.0 1.5 1.5 1.5 131.9 146.8 133.9 146.9 2.0 2.0 2.2 2.4 111.0 123.0 125.1 145.2 2.5 2.5 2.8 2.8 134.3 144.5 143.7 146.9 3.0 3.0 3.2 3.3