The business manager of a large corporation wanted to determine whether there was a difference between what salesmen spend on lunch and what executives spend on lunch. A sample of 8 salesmen indicated that they spent an average of $10.77 with a sample standard deviation of 0.24 on lunch. A sample of 10 executives indicated that they spent an average of $11.30 with a sample standard deviation of 0.56 on lunch. Let = 0.05. What are the critical values?