(a) Test the hypothesis Ho: σ =σ against H₁: σ σ using α = 0.05, and draw conclusions. 10-23. In semiconductor manufacturing, wet chemical etching is often used to remove silicon from the backs of wafers prior to metallization. The etch rate is an important characteris- tic 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 each solution. The observed etch rates are as follows (in mils per minute): Solution 1 Solution 2 9.9 10.6 10.2 10.0 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) Construct normal probability plots for the two samples. Do these plots provide support for the assumptions of normal- ity and equal variances? Write a practical interpretation for these plots. (b) Do the data support the claim that the mean etch rate is the same for both solutions? In reaching your conclusions, use α = 0.05 and assume that both population variances are equal. Calculate a P-value. (c) Find a 95% confidence interval on the difference in mean etch rates.