Question

A new purification unit is installed in a chemical process. Before the installation, a random sample yielded the following data about the percentage of impurity:

₁=9.85, s₁² =6.79, and n₁= 10. After installation, a random sample resulted in ₂=8.08, s₂² =6.18, and n₂= 8.

1. Can you conclude that the two variances are equal? (use a = 0.05 ).

2. Can you conclude that the new purification device has reduced the mean percentage of impurity? (use a = 0.05 ).

Answer 1