1. A real estate investor has two houses: A and B. Each house may increase in value, decrease in value, or remain unchanged. Consider the experiment of investing in the two houses and observing the change (if any) in value:

a. How many experimental outcomes are possible?

b. Show a tree diagram for the experiment.

c. How many of the experimental outcomes result in an increase in value for at least one of the two houses?

d. How many of the experimental outcomes result in a decrease in value for both of the houses?

2. A student has to take five courses to graduate. If none of the courses are prerequisites for others, how many groups of two courses can he or she select for the coming semester?

3. Suppose a salesperson makes a sale on 25 percent of customer contacts. In a normal work week, the salesperson contacts 30 customers.

a. What is the probability that the salesperson will make no sales?

b. What is the probability that the salesperson will make at least two sales?

c. What is the probability that the salesperson will make two sales at most?