A concrete cures it gains strength. The following data represent 7 days and 28 day strength in pounds per square inch (psi) of a certain type of concrete.

7 day strength psi, x        3330     2620     3380     2300     2480

28 day strength psi, y      4850     4190     5020     4070     4120

a) Compute the standard error of the estimate, Se. Se≈(......) (Do not round until  the final answer, Then round to four decimal places as needed)

b) Determine whether the residuals are normally distributed

c) If the residuals are normally distributed,  determine Sb1

d) If the residuals are normally distributed, test whether a linear relation exists between 7 day strength and 28 day strength a= 0.05 level of significance.

e) If the residuals are normally distributed construct a 95% confidence interval about the slop of the true least squares regression line.

f) What is the estimate mean 28 day strength of this concrete if the 7 day is 3000 psi?