2.  Probability is the mathematics
of chance.
 It can be written as a fraction,
decimal, percent, or ratio.
It tells us a result with
which we can expect an event
to occur

3. – an operation which
produces well-defined outcomes is called
an experiment .
– an experiment
when repeated under identical condition,
does not produce the same result, is
known as a random experiment.
– a result of some activity or
experiment is known as outcome.
– the collection of some or all
possible outcomes of an experiment is
called an event.

4. Value is between 0 and 1.
Sum of the probabilities of all
events is 1
Probability is the numerical
measure of the likelihood
that the event will occur.
Certai
n
Impossi
ble
50/50
.5
1
0

5. S.N Experiment Outcomes Some events
1 Tossing a coin Head(h)
Tail (T)
•H is the event of getting a head.
T is the event of getting a tail.
2 Rolling a dice 1,2,3,4,5,6 Getting an odd no is the event containing 1,3,5.
Getting a prime number is the event containing 2,3,5.
Getting a number greater than 5 is the event
containing 6 and so on.
3. Tossing two
coins
simultaneously.
HH,HT,TH,TT HH is the event of getting head on each coin.
HT is the event of getting head on 1st coin and tail on
2nd coin
TH is the event of getting tail on 1st coin and Head on
2nd coin.
TT is the event of getting tail on each coin.
.

8.  The probability of an event , E.
Number of Event Outcomes
P(E) =
Total Number of Possible Outcomes in S
Each of the outcomes in the sample
space are random and equally likely
to occur .
 E.g p( ) = 2/36 = 1/18
(There are 2 ways to get one 6 and
the other 4)

9.  There are three types of probability
 1. Theoretical Probability
 Theoretical probability is used
when each outcome in a sample
space is equally likely to occur.
P(E) ==
Number of Event Outcomes
Total Number of Possible Outcomes in S
The Ultimate probability formula 