Question: Sociology: Ethics

The one-time fling! Have you ever purchased an article of clothing (dress, sports jacket, etc.), worn the item once to a party, and then returned the purchase? This is called a one-time fling. About 10% of all adults deliberately do a one-time fling and feel no guilt about it! In a group of seven adult friends, what is the probability that

a.) No one has done a one-time fling?

b.) At least one person has done a one-time fling?

c.) No more than two people have done a one-time fling?