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 mea- surements (in angstroms x 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 x 1000 A. Use a = 0.05 and assume a two- sided alternative. (b) Find a 99% two-sided confidence interval on mean photoresist thickness. Assume that thick- ness is normally distributed