A flu virus hits a company employing 180 people. Independent of the other employees, there is a

Question:

A flu virus hits a company employing 180 people.
Independent of the other employees, there is a probability of p = 0.35 that each person needs to take sick leave. What are the expectation and variance of the proportion of the workforce who need to take sick leave? In general, what value of the sick rate p produces the largest variance for this proportion?