Answer:
2 Six graders: 6/55 chance
2 Seventh graders: 21/55 chance
Explanation:
Total: 11 students
6 graders: 4
4/11 for first student and 3/10 for second
4/11 * 3/10 = 12/110 = 6/55
7 graders: 7
7/11 for first student and 6/10 for second
7/11 * 6/10 = 42/110 = 21/55