Question

QUESTION 1: (20 pts) A new process has been developed for applying photoresist to 125-mm silicon wafers used in manufacturing integrated circuits. Twenty wafers were tested, and the following photoresist thickness measurements in angstroms x 1000) were observed: Wafer 1 2 3 4 5 6 thickness 13.39 13.37 13.39 13.41 13.43 13.41 13.40 13.38 13.42 13.39 Wafer 11 12 13 14 15 16 17 18 19 20 | thickness 13.39 13.40 13.42 13.42 13.40 13.40 13.37 13.37 13.43 13.43 12.20 13.39 13.41 13.40 13.40 Assuming that the thickness is normally distributed, we got t = 13.40, s = 0.0172 (a) construct the 95% Confidence Interval for the mean diameter of the rod. (b) construct the 95% Confidence Interval for the variance of the diameter. (c) based on the Confidence Interval from (a), can we be assured that the mean thickness is at 13.41 (angstroms x 1000) with a=5%.

Answer 1

V20 Question 1: Degrees of freedom ani= 20-1219 en The 954. confidence interul for the mean (h)= atten = 13.40 I (20934 002)=(123920, 13:4080) The 95%. CI for l= (13.392, 13.408) (b) The art. Confidence interval for population Variance of (n-us (-)s² a x6.0172)2 19x6.01728² 2 X2-X13 8.9065 32.8523) . The 95% CI for six (6.000 171 0.000631) C) No the because mean thickness cannot be 13.41 (angostingly the art. cI not Contains 13.41