She only asked the students in her ballet class, which is probably biased toward ballet. She should survey everyone in The Dance Academy. That way, the answers won't be biased.
1. 3/6 = 1/2
2. 5/6
3. 3/6 : 3/6 = 3 : 3
4. 3/6 : 3/6 = 3 : 3
5. 5/6 : 1/6 = 5 : 1
7. 3/6 × 1/2 = 1/4