Use the Following Information for Questions

Short Answer

Use the following information for questions:
A union representative has collected some data on the hourly pay of workers in the area. He is curious to find out if hourly pay actually increases with age. He does not have the actual ages of the workers in his sample, but he does have age group information. For now, he wishes to compare the young workers (18-30 years old) with the middle aged workers (31-45 years old) by calculating a confidence interval for the difference in population mean salaries.
-How would the 99% confidence interval for the difference in average hourly pay compare to the 90% confidence interval?