11TH GRADE
INTRODUCTION TO
PROBABILITY
STATISTICS AND PROBABILITY
2ND SEM LESSON 1
LESSON’S OBJECTIVES
● Recall the definition of Probability of occurrence of
event.
● Illustrates a random variable (discrete and continuous)
● Distinguishes between a discrete and a continuous
random variable
What is Probability?
If 100 students will participate in a raffle game,
what is the chance of winning the prize?
Probability is the extent to which the event is
likely to occur, measured by:
𝑁𝑜.𝑜𝑐𝑐𝑢𝑟𝑟𝑒𝑛𝑐𝑒 𝑜𝑓 𝑒𝑣𝑒𝑛𝑡 𝐴 𝑛(𝐴)
𝑃 𝐴 = = 𝑛(𝑆)
𝑁𝑜.𝑜𝑓 𝑎𝑙𝑙 𝑝𝑜𝑠𝑠𝑖𝑏𝑙𝑒 𝑜𝑢𝑡𝑐𝑜𝑚𝑒𝑠
Random Variable
A random variable is called
discrete if it has either a finite or a countable
number of possible values. Thus, a
discrete random variable X has possible values
x1,x2, x3,....
A random variable
is called continuous if its possible values
contain a whole interval of numbers.
.
Discrete Random Variable
Example:
Discrete Random Variable
1. Number of heads in 4 flips of a coin
(possible outcomes are 0, 1, 2, 3, 4)
2. Number of classes missed from March 2020
to December 2020
3. The number of siblings a person has
4. The number of Covid-19 cases in Negros
Oriental in 2020
5. The number of students involve in Online
classes in Neg Or Division
during this pandemic time
.
Continuous Random Variable
Example:
Continuous Random Variables
1. Heights of students in class
2. Time to finish a module
3. Hours spent exercising
4. Distance travelled from Dumaguete to
Pamplona.
Example 1
Suppose you tossed 3 coins, these are the list of all
possible outcomes.
LIST OF ALL OUTCOMES
HHH HTT
HHT THT
HTH TTH
THH TTT
Consider the Event A of Getting 2 heads and 1 tails.
Probability of getting 2 heads and 1 tail is
3
𝑃 𝐴 = 𝑃 2𝐻1𝑇 =
8
Example 2
Suppose you tossed 3 coins, these are the list of all
possible outcomes.
LIST OF ALL OUTCOMES
HHH HTT
HHT THT
HTH TTH
THH TTT
Consider the Event B of getting exactly 1 head.
Probability of getting exactly 1 H
3
𝑃 𝐵 = 𝑃 1𝐻 =
8
Example 3
Suppose you tossed 3 coins, these are the list of all
possible outcomes.
LIST OF ALL OUTCOMES
HHH HTT
HHT THT
HTH TTH
THH TTT
Consider the Event C getting exactly 3 Tails
Probability of getting exactly 3 T
1
𝑃 𝐶 = 𝑃 3𝑇 =
8
Example 4
Suppose you roll a Fair Die? These are all the possible
outcomes
LIST OF ALL OUTCOMES
1 2
3 4
5 6
Consider the Event S of getting EVEN NUMBERS.
Probability of getting Even numbers is
3 1
𝑃 𝑆 = 𝑃 𝐸𝑉𝐸𝑁 = =
6 2
Let’s Practice few
Examples
TRY THIS!!!
A bag contains 7 white balls and 11 orange balls.
If the ball is drawn at random from the bag, find the Probability that the
ball is:
Probability of getting Green
1. Green. 0
𝑃 𝐺 = =0
2. White.
18
3. Not White.
TRY THIS!!!
A bag contains 7 white balls and 11 orange balls.
If the ball is drawn at random from the bag, find the Probability that the
ball is:
Probability of getting White
1. Green. 7
𝑃 𝑊 =
2. White. 18
3. Not White.
TRY THIS!!!
A bag contains 7 white balls and 11 orange balls.
If the ball is drawn at random from the bag, find the Probability that the
ball is:
Probability of getting Not White
1. Green. 11
𝑃 𝑌 =
2. White. 18
3. Not White.
Activity No. 1
1. Assuming you are tossing a fair die. What is the
Sample Space?
Find the Probability of getting:
a. An odd number
b. A number greater than or equal to 3
c. A number less than 6
d. An even number
Activity No. 1
2. Suppose a box of Marbles has the following
colors. 6 Red marbles, 5 Black Marbles, 2 Blue
Marbles, and 2 White Marbles. Find the
probability of getting:
a. White Marble.
b. Red Marble
c. Yellow Marble
d. Blue Marble
Activity No. 1
3. After a certain survey with total of 100
people around Sapang Palay, there 23 person
who commute when going to work, 11 person
use Private automobile and 17 people use E-
bike as transportation. What is the Probability
that the person interviewed use:
a. Commuter c. Private Automobile
b. E-bike d. Not E-bike user
Thank you for
listening!!
Do you have any
question??