Refer to the data for problem 6. Select the two additives with the largest average difference in waste and answer the following. (Use the least-significant-difference test method for this problem, subtracting smaller from larger even if you feel that it is not appropriate to do so.)
a. Find the size of the average difference for this pair.
b. Find the standard error of this average difference.
c. How many degrees of freedom does this standard error have?
d. Find the two-sided 90% confidence interval for the mean difference.
e. Based on the average difference, the standard error, the degrees of freedom, and the t table, do these two additives appear to be significantly different at the 10% test level?
f. Can you conclude that the two additives are really significantly different at the 10% level? Why or why not? (Be careful. You may wish to consider the result of the F test from the preceding problem.)