The human resources department of a consulting firm gives a standard creativity test to a randomly selected group of new hires every year. This year, new hires took the test and scored a mean of points with a standard deviation of . Last year, new hires took the test and scored a mean of points with a standard deviation of . Assume that the population standard deviations of the test scores of all new hires in the current year and the test scores of all new hires last year can be estimated by the sample standard deviations, as the samples used were quite large. Construct a confidence interval for , the difference between the mean test score of new hires from the current year and the mean test score of new hires from last year. Then find the lower limit and upper limit of the confidence interval.