Probability
By
Dr. Louay A. Aboul-Nour
What is Probability?
• Probability is the likely hood of an
event to occur.
Example : Flipping a coin.
What is the likely hood of the
event “getting a head”?
Immediately you will say
“once every two tosses”
Which is a probability of 1/2
or the event has a 50% chance.
What is an Event?
• An event is a specific result
happening
Example :
An event could be
A team “winning the cup”
The sky “raining tomorrow”
A “fish living in water”
An “elephant flying”
A Sure or Certain Event?
• Is an Event that ALWAYS happens
Example :
A Certain Event
A “cork floating on water”
A “rock falling down”
A certain event has a 100% probability
An Impossible Event?
• Is an Event that Never happens
Example :
An Impossible Event
A “Fish living out of water”
An “Elephant flying in the sky”
An impossible event has a 0% probability
Probability Range
• Probability of any event ranges
from an impossible event value to
a certain event value.
Since :
Impossible Events have 0% probability
Certain events have 100% probability
Then : Probability lies between
Percentages
Decimal Form
0%
0.0
and 100 %
and 1.0
The Experiment
• The experiment is a process that
results in an out come.
Example #1 : Flipping a coin once
The experiment here is the process of
flipping the coin just one time.
Example #2 : Rolling a die once
The experiment here is the process of
rolling the die just one time.
Possible Outcomes
• The outcome is any possible result
that can occur from experiment.
Example #1 : Flipping a coin once
The outcome is either “Head “ or “Tail”.
Possible Outcomes are only TWO
Example #2 : Rolling a die once
The outcome is either “1,2,3, 4,5 or 6“ ”.
Possible Outcomes are SIX