There's 12 true or false questions in a test. A student decides to guess the answers. Answer the following questions. Note: The calculation must be shown on every single one.

1- What's the probability of the student failing all questions (0/12)?

2- What's the probability of the student obtaining a perfect score (12/12)?

3- What's the probability of the student obtaining 9 or more correct answers?

4- What's the probability of the student obtaining 5 or less correct answers?