A new purification unit is installed in a chemical process. Before and after installation data was collected regarding the percentage of impurity:
Before (1): Sample mean = 9.85, Sample variance = 6.79, Number of samples = 10
After (2): Sample mean = 8.08, Sample variance = 6.18, Number of samples = 8
a. Can you conclude that the two variances are equal using a two-sided 95% confidence interval?
b. Can you conclude that the new purification device has reduced the mean percentage of impurity using a two-sided 95% confidence interval?