Question about Finding a probability based on a table

1. How many ways can 15 girls be chosen to form a baseball team (need 9 players)?

5005
1,816,214,400
24
135

3. Use this table to answer questions #3 through #6. Some students were asked if they carry a credit card. Here are the responses.
Class______ | Credit Card Carrier | Not a Credit Card Carrier | Total
Freshman______________33_______________________27________________60
Sophomore______________6_______________________34________________40
Total__________________39_______________________61________________100
What is the probability that the student didn't carry a credit card?

4. What is the probability that the student is a freshman and carries a credit card?

5. What is the probability that the student is a sophomore given he doesn't carry a credit card?

6. Are Credit Card Carriers and Freshmen independent events? Prove this mathematically