Please help with the following question.

1. A group of researchers has estimated that the probability with which a teacher retires in any given year is 0.3. (a) (2 points) A school currently has 5 teachers in third grade. What is the probability that 3 of them will retire next year? (b) (3 points) A school currently has 5 teachers in third grade. What is the probability that most of them will retire next year? (c) (4 points) A school district has 500 teachers. What is the probability that more than 160 of them will retire next year? (d) (4 points) What is the probability that a given teacher has retired within the next three years