refresher
Dealing with ONE "event" ...
Simple Event
(or single event)
A simple (or single) event is an event with a single outcome.
  Simple Probabilities (with only one outcome (desired result)):
• The probability of rolling a 3 on a die. (1/6)
• The probability of drawing the ace of hearts from a deck of cards. (1/52)
• The probability of tossing a head with a penny. (1/2)
• The probability of rolling an even number less than 5 on a die. (2/6 = 1/3)

     defpossible
 cointoss

dividerdash


Dealing with MORE THAN ONE "event" ...
Compound Event
A compound event is the combination of two or more simple events (with two or more outcomes).
 
Compound Probabilities (with more than one outcome, or desired result within a trial ):
• The probability of rolling an even number on a die, then tossing a head on a    penny. (3/12 = 1/4)
• The probability of tossing three pennies and getting at least 2 heads.
   (4/8 = 1/2)    
• The probability of drawing a heart from a deck of cards, replacing the card,
   then drawing a spade.  (169/2704 = 1/16)
• The probability of drawing a red ace from a deck of cards, not replacing
   the card, then drawing a black ace. (2/52 • 2/51 = 4/2652 = 1/663)
talking deck
         
         Independent events: multiply the two probabilities
         Dependent events (one affects the other): multiply the probability of the first event
         times the probability of the next event after the first event has taken place. 

dividerdash


 
Remember: When dealing with probability (especially compound probability), a tree diagram may be helpful to "see" what is happening.
cardsdice


divider


NOTE: The re-posting of materials (in part or whole) from this site to the Internet is copyright violation
 and is not considered "fair use" for educators. Please read the "Terms of Use".