In semiconductor manufacturing, wet chemical etching is often used to remove sil

Question

In semiconductor manufacturing, wet chemical etching is often used to remove silicon from the backs of wafers prior to metalization. The etch rate is an important characteristic in this process and known to follow a normal distribution. Two different etching solutions have been compared, using two random samples of 10 wafers for etch solution. The observed etch rates are as follows (in mils/min): Test the hypothesis H_0: sigma^2_1 = sigma^2_2 against H_1: sigma^2_1 notequalto sigma^2_2 using alpha =.05. What is the test statistic? Round your answer to 3 decimal places.

Explanation / Answer

Using Minitab:

Test and CI for Two Variances: Solution1, Solution2

Method

Null hypothesis         (Solution1) / (Solution2) = 1
Alternative hypothesis (Solution1) / (Solution2) 1
Significance level      = 0.05

Statistics

                                  95% CI for
Variable    N StDev Variance      StDevs
Solution1 10 0.381     0.145 (0.238, 0.756)
Solution2 10 0.220     0.048 (0.140, 0.430)

Ratio of standard deviations = 1.729
Ratio of variances = 2.991

95% Confidence Intervals

                             CI for
         CI for StDev       Variance
Method       Ratio           Ratio
Bonett (0.749, 3.885) (0.562, 15.090)
Levene (0.772, 5.019) (0.596, 25.192)

Test Statistic=Ratio of variances = 2.991

Hope this will be helpful. Thanks and God Bless You :)

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