A personnel director wishes to compare the effectiveness of two methods for training employees to perform a certain assembly operation. Employees are to be divided into two equal groups: the first receiving training method 1 and the second training method 2. Each will perform the assembly operation, and the assembly time will be recorded. The director expects that the assembly times for both groups will have a range of approximately 8 minutes, and he wants the estimate of the difference in mean times to assemble to be correct to within 1 minute with a probability equal to .95. How many workers must be included in each training group?