Discrete and Continuous Random Variables (Jump to: Lecture | Video )

Random Variable

A random variable is a variable which has its value determined by a probability experiment.

If you flip a coin once, how many tails could you come up with? Let's create a new random variable called "T". "T" represents the number of tails possible from our probability experiment. After flipping a coin once (a probability experiment), T's value will be either 1 or 0. T is a random variable.

Discrete Random Variable

A discrete random variable is a random variable which has a finite number of values.

Letís say you flip a coin six times. How many tails could you come up with?

Figure 1.

There are a finite number of possible values. Values such as "1.5" or "2.5923" donít make sense for this type of problem.

Continuous Random Variable

A continuous random variable is a random variable which has an infinite number of values.

Letís say you measure the speed (in miles per hour) of the first car to drive by your house. What kind of values could you obtain?

Figure 2.

Maybe the car is going 25mph, or 50mph, or 62.00252mph. The variable (speed) can take on an infinite number of values.


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