Introductory Statistics Lesson 4.1 A Objective: SSBAT distinguish between discrete random variables and continuous random variables Standards: S2.5B

Random Variable, x  Represents a numerical value associated with each outcome of a probability experiment.  The word Random indicates that x is determined by chance  There are 2 types of random variables: Discrete and Continuous

Discrete Random Variable  A random variable that has a finite or countable number of possible outcomes  The outcomes can be listed  The outcomes can be shown as just points on a number line  Examples: The number of students in a class The number of patients in a doctor’s surgery The number of calls a salesperson makes in a day

Continuous Random Variable  A random variable that has an uncountable number of possible outcomes  All of the outcomes cannot be listed  The outcomes can be shown as an interval on a number line  It can be a continuous flow from one amount to another  Examples: The time it takes to run a mile The time spent on phone calls during a given day

Ex.: Determine if each random variable is Discrete or Continuous 1.The amount of water in a 32 ounce container  Continuous - the amount can be any number of ounces between 0 and 32

Ex.: Determine if each random variable is Discrete or Continuous 2. The number of songs played by a band  Discrete - the number of songs played by a band is countable

Ex.: Determine if each random variable is Discrete or Continuous 3. The length of time it takes to complete a test  Continuous – it includes all measurements of time from start to finish (can include fractional amounts) 4. The height of a tree at a nursery  Continuous – it can be any height - A tree can be 70 inches A tree can be 70.1 inches A tree can be inches, etc

Ex.: Determine if each random variable is Discrete or Continuous 5. The number of suitcases lost by an airline  Discrete 6. The number of skittles in a bag  Discrete 7. The weight of newborn babies  Continuous

Discrete Random Variables are usually: 1.When you are counting something 2.There are only a certain amount of numbers 3. Usually include whole numbers

Continuous Random Variables are usually: 1.Amounts that can include fractions or decimals 2.Amounts that are associated with Measuring something (weights, heights, time, etc) 3.They include all numbers within an interval - All values between 0 and 20

Complete Worksheet 4.1 A