EX 3.6

• All random variables in Examples 3.1-3.4 are:
  • Discrete
• Additional example:
  • Scenario:
    • Selecting married couples at random
    • Performing blood tests on each person
    • Goal: Find a husband and wife with the same Rh factor
• Definition:
  • Let $X$ = number of blood tests performed
• Possible values of $X$:
  • $D=\{2,4,6,8,\dots \}$
• Conclusion:
  • Since possible values are listed in sequence, $X$ is:
  • A discrete random variable (rv)