Probability of events

1. PROBABILITY OF EVENTS

2. Believe It or Not!
Analyze the situation below:
1. Fitting your
wedding dress prior
to your wedding day
will cost you your
life.
2. Sweeping the
floor at night
will bring you
bad luck
3.When a woman
sings while
cooking, she will
end up a spinster
4.When three
people pose for a
picture, the one at
the center will be
the first to die.
5. Crossing paths with a black cat is a
bad omen.

3. Match the following situation below with the
probability line.
Match Me with the Probability Scale
1.There are 7 days in a week.
2.Outof 20 items, Christine Bethel got 15.
3.In the Philippines, it will snow in March
4.If you flip a coin, it will come down head.
5.All months of the year have 28 days.
6.It will be daylight in Manila at midnight.
7.The day before Monday is Sunday.
8.Of the 40 seedlings, only 10 survived.
9.The third person to knock on the door will be a female.
10.Next year, the month after November has 30 days.

4. Things to Remember
EXPERIMENTS
A situation involving chance or probability that leads
to results called OUTCOMES.Ex: Head or Tail
Ex: Flipping a coin
SAMPLE SPACE
is the set of all outcomes in an experiments.
Ex: Head, Tail
EVENT
one or more outcomes of an experiment.
Ex: getting head in a single toss.
PROBABILITY
is the measure of how like an event is.
Ex: ½ or .5 or 50%
SIMPLE EVENT
an event which consist of one outcome.
COMPOUND EVENT
are event which consist of more than one outcome.

5. Probability Rules:
Never to
happen
Sure to
happen
1. The probability of any event is a number from 0 to 1.
Ex: The weather forecast shows a 70% rain.
2.If an event will never happen,then its probability is 0.
Ex:What is the probability of getting 8,when single die is
rolled.
3.If an event is sure to happen, then the probability is 1.
Ex:What is the probability of getting a number less than 7
when a single die is rolled.
4. The sum of the probabilities of all outcomes in the sample
space is 1.

6. Probability of Events
Probability of Simple Events(is a number from 0 to 1
which tells how likely the event is to happen)
If each of the outcomes in a sample space is
equally likely to occur, then probability of an event E,
denoted as P(E) is given by:
P(E) = number of ways the event can occur
Number of possible outcome
or
P(E)= number of outcomes in the event
Number of outcomes in the sample space

8. Based on the answers above,
it can be concluded that the
word “or” is related to union of
sets and “and” is connected to
intersection of sets.

9. Union and Intersection of Events

11. When you were in Grade 8, you learned
different terms in finding probability of a
simple event. Some of them are as
follows:
a. Experiment – an activity which could be
repeated over and over again and
which has well- defined results.
b. Outcome – a result of an experiment
c. Sample Space – a set of all outcomes
in an experiment
d. Event – a subset of the sample space

16. If you were asked to select a set of order, then, you
have to choose between the two kakanin, between the two
kind pastas, and between the two drinks.
Then, sample space : {(sinukmani, spaghetti, pineapple
juice), (sinukmani, spaghetti, orange juice), (sinukmani,
palabok, pineapple juice), (sinukmani, palabok, orange
juice), (puto, spaghetti, pineapple juice), (puto, spaghetti,
orange juice), (puto, palabok, pineapple juice), (puto,
palabok, orange juice)}.
What if you were asked of the number of outcomes
in selecting an order of merienda with sinukmani and with
pineapple juice?
Based from the illustration, there are two outcomes
for the given event which are (sinukmani, spaghetti,
pineapple juice) and (sinukmani, palabok, pineapple juice).

17. You can recognize that the events
in the given situation are not simple
events. In finding the sample, you need
to find first the sample space using the
fundamental counting principle. The said
events are called compound events. It is
defined as events which consist of more
than one outcome.
A compound event consists of two
or more simple events.

20. Example 4. Let’s take
again Figure 1 that is
discussed, previously. The
extracurricular activities in
which the Grade 10
students of San Jose
National High School
during the School Year
2019-2020 participated
are shown.

24. Learning Task 2
Find the union and intersection of
events A and B defined by the
following situations. 1. A four-section
spinner marked red, yellow, blue, and
black is spun once and a five peso
coin is tossed once. A is the event of
spinning a yellow and B is the event
of getting a head.
2. A die is tossed twice. A is the event
of getting equal dots and B is the
event of getting a sum of 8

25. Performance Task
During the quarantine period due to
COVID-19, everybody was affected. People were afraid
that the virus may infect them. Fake news flooded in
social media that increase worries to the people. The
government set the standard rules to be followed by
everybody. They encourage everyone to stay at home. 1.
What are the common problems encountered during the
quarantine period? 2. What are your reactions
regarding the fake news that flooded in social media
during the quarantine period?

26. Thank You for
listening.....
Riza B. Catli