Independent or Dependant … THAT is the question!

Calculating the Probability of Independent and Dependent Events

Chapter 4

Professor Linda WilliamsBUS216

Two or more events are Independent Events if the occurrence or nonoccurrence of one of the events does not effect the occurrence or nonoccurrence of the other event(s)

Flipping a coin Rolling a single die Being left-handed and owning a dog Eating popcorn and singing Broadway show tunes

Examples of Independent Events:

Two or more events are Dependent Events if the occurrence or nonoccurrence of one of the events does effect the occurrence or nonoccurrence of the other event(s)

Attending college and graduating from High School Drawing 2 cards from a deck without replacement Picking students for teams in Dodge Ball

Examples of Dependent Events:

Calculation of Probabilities

Sample space DECREASES

Sample Space UNCHANGED

Dependent Events Independent EventsP(3 Aces in a Row)

=P(3 Aces in a Row) =

The Defective Part Dilemma …A box contains 15 parts, 3 of which are defective.

(A) If you randomly select two parts from the box, without replacement, what is the probability that both parts are defective?

(B) If you randomly select two parts from the box, with replacement, what is the probability that both parts are defective?

Summary

First: Determine if the events effect the outcome of one another!

If Dependent – BOTH the sample size and likelihood of success decrease in each event

If Independent – the sample size and the likelihood of success remain fixed in each event