A new process has been developed for applying photoresist to 125-mm silicon wafers used in manufacturing integrated circuits. Ten wafers were tested, and the following photoresist thickness measurements (in angstromx × 1000) were observed: 13.3987, 13.3957, 13.3902, 13.4015, 13.4001, 13.3918, 13.3965, 13.3925, 13.3946, and 13.4002.
(a) Test the hypothesis that mean thickness is 13.4 × 1000 Å. Use a = 0.05 and assume a two-sided alternative.
(b) Find a 99% two-sided confidence interval on mean photoresist thickness. Assume
(c) Does the normality assumption seem reasonable for these data?