Continuous Probability
Distributions
Lecturer
K M Muhaiminul Nafiu
AhsanullahUniversity of Science and Technology
Continuous Variable
•A continuous random variable can assume any value over an interval or
intervals
Probability Sums
•The Normal Distribution
•A large number of phenomena in the real world are approximately
normally distributed.
Thecontinuousrandomvariablesrepresentingheightsandweightsof
people,scoresonanexamination,weightsofpackages(e.g.,cereal
boxes,boxesofcookies),amountofmilkinagallon,lifeofanitem
(suchasalight-bulboratelevisionset),andtimetakentocompletea
certainjobhaveallbeenobservedtohaveanapproximatenormal
distribution.
Normal Distribution
The Standard Normal Distribution
Standardizing a Normal Distribution
Thezvaluesontherightsideofthemeanarepositiveandthoseontheleftsidearenegative.Thezvaluefora
pointonthehorizontalaxisgivesthedistancebetweenthemeanandthatpointintermsofthestandarddeviation.
For example, a point with a value of Z = 2 is two standard deviations to the right of the mean. Similarly, a
point with a value of Z =-2 is two standard deviations to the left of the mean.