Consider Supplemental Exercise 10-72. Suppose that prior to collecting the data, you decide that you want the error in estimating σ1 = σ2 by x1 = x2 to be less than 1.5 psi. Specify the sample size for the following percentage confidence:
(a) 90%
(b) 98%
(c) Comment on the effect of increasing the percentage confidence on the sample size needed.
(d) Repeat parts (a)–(c) with an error of less than 0.75 psi instead of 1.5 psi.
(e) Comment on the effect of decreasing the error on the sample size needed.