Random Variables

• A random variable X maps each outcome s in the sample space S to a real number .
• Example: A fair coin is tossed 3 times.

  

  Let X be the number of heads tossed in 3 tries.
  

  

• So

  

• Random Variable as a Measurement
• Probability Mass Function for a Random Variable
• Cumulative Distribution Function
  • PMF and CDF for the 3 Coin Toss Example
• Expectation of a Random Variable