g 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 characteristic in this process and known to follow a normal distribution. Two di erent 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 9.9 9.4 9.3 9.6 10.2 10.6 10.3 10.0 10.3 10.1 Solution 2 10.2 10.6 10.7 10.4 10.5 10.0 10.2 10.7 10.4 10.3 a. Calculate the sample mean and standard variance for each sample. b. Conduct a hypothesis test to test whether the mean etching rates are the same for the two different solutions at 0.05 level of significance. c. What assumptions are required to ensure the validity of the test in (b)