7! 8C8 4! Calculate the following. (4 points each) 4. Each employee at the business has a security code. The code is made from three different letters followed by two different numbers. Find how many different security codes can be generated. 5. In a board of directors composed of 14 people, how many different ways can one chief executive officer, one director, and one treasurer be selected? 6. A committee of five students is to be selected at random from a pool of eighteen freshmen and twelve sophomores. What is the probability that the committee has three freshmen and two sophomores? '7. A corporation of 100 calculators contains three defective calculators. If four calculators are chosen at random, find the probability of selecting one defective calculator and three good calculators