I do not understand what is meant by “a student decides to check six of each at random”

Does it mean “how many ways can she chose 6 questions to answer?”

Or does it mean “how many ways can she answer 6 questions?”

Or does it mean “how many ways can she chose and then answer 6 questions?”

How many ways can a committee of 3 be chosen from 20 people: .

In how many ways can a president, a secretary and a treasurer be chosen?