Comparing dexterity-test scores of workers on the day shift versus those on the night shift, the production manager of a large electronics plant finds that a sample of 37 workers from the day shift have an average score of 73.1, with a standard deviation of 12.3. For 42 workers from the night shift, the average score was 77.3, with a standard deviation of 8.4.
Assuming the population standard deviations are equal, use the 0.05 level of significance in comparing the average scores for the two shifts. Using the appropriate statistical table, what is the most accurate statement we can make about the p-value for this test?
Construct and interpret the 95% confidence interval for the difference between the population means.