How tall is your average STAT252 classmate? To determine this, you measure the height of 26 fellow students from your computer lab and find a sample standard deviation of 2.1 inches. Construct a 90 percent confidence interval for the mean height of your classmates (round your results to 3 decimal places). a. the critical value for right-hand area of a/2 = b. the critical value for right-hand area of 1-a/2= c. Upper bound of the confidence interval= d. Lower bound of the confidence interval=