I have no idea how to solve this problem

A survey of undergraduate calculus and physics students showed that 58% of them had donated blood at
least once.
6. What is the probability that in any undergraduate class of 30 calculus and physics students there are
exactly 20 students that have donated blood at least once?
7. What is the probability that in any undergraduate class of 30 calculus and physics students there are
at most 20 students that have donated blood at least once?
8. What is the probability that in any undergraduate class of 30 calculus and physics students there are
at least 20 students that have donated blood at least once?
9. Find the mean and standard deviation of this distribution.