A 99% CI on the difference between means will be (longerthan/wider than/the same length as/shorter than/narrower than )a95% CI on the difference between means.
In semiconductor manufacturing, wet chemical etching is oftenused to remove silicon from the backs of wafers prior tometalization. The etch rate is an important characteristic in thisprocess and known to follow a normal distribution. Two differentetching solutions have been compared, using two random samples of10 wafers for each solution. Assume the variances are equal. Theetch rates are as follows (in mils per minute):
Solution 1 | | Solution 2 |
9.8 | 10.2 | | 10.6 | 10.4 |
9.4 | 10.3 | | 10.6 | 10.2 |
9.3 | 10.0 | | 10.7 | 10.7 |
9.6 | 10.3 | | 10.4 | 10.4 |
10.2 | 10.1 | | 10.5 | 10.3 |
(a) Calculate the sample mean for solution 1: x¯1=  Roundyour answer to two decimal places (e.g. 98.76).
(b) Calculate the sample standard deviation for solution 1:s1 =Â Â Round your answer to threedecimal places (e.g. 98.765).
(c) Calculate the sample mean for solution 2: x¯2=  Roundyour answer to two decimal places (e.g. 98.76).
(d) Calculate the sample standard deviation for solution 2:s1 =Â Â Round your answer to threedecimal places
(e) Test the hypothesis H0:μ1=μ2 vs H1:μ1≠μ2.
Calculate t0 =Â Â Round your answer totwo decimal places (e.g. 98.76).
(f) Do the data support the claim that the mean etch rate isdifferent for the two solutions? Use α=0.05.                   yesno
(g) Calculate a 95% two-sided confidence interval on the differencein mean etch rate.
(Calculate using the following order: x¯1-x¯2)
(   ≤ μ1-μ2 ≤  ) Round your answers tothree decimal places (e.g. 98.765).
