The coefficient of absorption (COA) for a clay brick is the ratio of the amount
ID: 2947389 • Letter: T
Question
The coefficient of absorption (COA) for a clay brick is the ratio of the amount of cold water to the amount of boiling water that the brick will absorb. An article presents measurements of the (COA) and the pore volume (in cm3/g) for seven bricks. The results are presented in the following table
a. Compute the least-squares line for predicting COA from pore volume. Round the answers to three decimal places
Y= 0.103+0.404X (already got and checked this)
b.Compute the error standard deviation estimate s. Round the answer to four decimal places
c. Compute a 95% confidence interval for the slope. Round the answers to three decimal places
d. Find a 95% confidence interval for the mean COA for bricks with pore volume 1.5 cm3/g. Round the answers to three decimal places
e. Find a 95% prediction interval for the COA of a particular brick whose pore volume is 1.5 cm3/g. Round the answers to three decimal places.
Pore Volume COA 1.750 0.8 1.632 0.78 1.594 0.77 1.623 0.75 1.495 0.71 1.465 0.66 1.28 0.63Explanation / Answer
a,b] Regression Analysis: COA versus Pore volume
Model Summary
S R-sq R-sq(adj) R-sq(pred)
0.0216328 90.52% 88.63% 82.12%
Coefficients
Term Coef SE Coef T-Value P-Value VIF
Constant 0.1035 0.0908 1.14 0.306
Pore volume 0.4037 0.0584 6.91 0.001 1.00
Regression Equation
COA = 0.1035 + 0.4037 Pore volume
c,d,e]
95% confidence interval for the slope
Prediction for COA
Regression Equation
COA = 0.1035 + 0.4037 Pore volume
Variable Setting
Pore volume 1.5
Fit SE Fit 95% CI 95% PI
0.709021 0.0086521 (0.687, 0.731) (0.649, 0.770)