2. Chapter 4: DISCRETE RANDOM VARIABLES2 Random variable is a numerical variable whose value is subject to variations due to chance. It is a numerical output from a random experiment. Examples: 1.Number of heads in ten flips of a coin. 2.Number of rings before the phone is answered. 3.Number of hits on a particular website within next hour. 4.Compressive strength of a tested concrete cylinder. 5.Lifetime of a bulb. 6.Discharge (streamflow) of a river.

3. Chapter 4: DISCRETE RANDOM VARIABLES3 A discrete random variable is a variable that can assume only a finite or infinite but countable number of values.  Very often (but not necessarily) its values are natural numbers.  See examples 1-3 on previous page. A continuous random variable is a variable that can assume any value in an interval (finite or infinite)  Its values are often decimal numbers.  See examples 4-6 on previous page.  We will discuss continuous variables in the next chapter.

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