Psychology: Myers–Briggs Approximately 75% of all marketing personnel are extroverts, whereas about 60% of all computer programmers are introverts

(Source: A Guide to the Development and Use of the Myers–Briggs Type Indicator, by Myers and McCaulley).

(a) At a meeting of 15 marketing personnel, what is the probability that 10 or more are extroverts? What is the probability that 5 or more are extroverts?

What is the probability that all are extroverts?

(b) In a group of 5 computer programmers, what is the probability that none are introverts? What is the probability that 3 or more are introverts? What is the probability that all are introverts?