A Manager Is Thinking of Providing, on a Regular Basis

A manager is thinking of providing, on a regular basis, in-house training for employees preparing for an inventory management certification exam. In the past, some employees received the in-house training before taking the exam, while others did not. Independent random samples taken from the company's records provided the following exam scores for 10 workers who did not receive in-house training and 8 workers who did receive training. (The manager is confident that the distributions of both populations' exam scores are approximately normal.)

a. Develop a 95% confidence interval estimate for the difference between the average test scores for the two populations of employees.
b. Using a = .05, test for any difference between the average test scores for the two populations of employees.