2. From a business class of 16 equally capable students using programmed materials, 5 are selected at random and given additional instruction by the professor. The results of the final examination were as follows: Students Grouping Grades Additional instruction 87, 79, 78, 91, 80, 82, 84, 79, 85 No additional instruction 75, 80, 64, 82, 83, 79, 67 Test with alpha = 0.05 to determine if additional instruction affects the average grade