Types of random variables at a health center. A health center is offering discounts to new customers. At the end of one month, the manager of the health center analyzes the data collected during the offer period. The following variables are of interest to the manager. Which are discrete and which are continuous random variables?

a. The revenue earned by the center at the end of the month.

b. The number of health packages sold at the end of the month.

c. The number of new customers who joined the center.

d. The percentage change in the center’s earnings between last month and this month.

e. The time spent approaching new customers and persuading them to join a health program.

f. The number of health products, such as slimming pills, exercise mats, and slimming tea, sold. Random variables that can assume a countable number (finite or infinite) of values are called discrete. Random variables that can assume values corresponding to any of the points contained in one or more intervals (i.e., values that are infinite and uncountable) are called continuous. M04_MCCL3396_14_GE_C04.indd 211 29/09/2021 14:00 212 CHAPTER 4 ● Random Variables and Probability Distributions