02_Probability of Compoujkjnd Events.ppt

Probability
of Compound
Events

Probability of Compound Events
Objective:
(1) Students will be able to find the probability
of a compound event.
(2) Students will be able to understand the
distinction between simple events and
compound events.
Essential Question:
(1) How do I find the probability of a compound
event?
(2) How can I distinguish between a simple and
compound event?

Vocabulary:
 Outcome – one possible result of a probability.
 Sample Space – the list of possible outcomes
for a probability event.
 Random – outcomes that occur at random if
each outcome is equally likely to occur.
 Compound Event – a specific outcome or type
of outcome.
 Complementary Events – the events of one
outcome happening and that outcomes not
happening are complimentary; the sum of the
probabilities of complementary events is 1.

What is a PROBABILITY?
- Previously we looked at probability
for simple individual events
- If a simple event involves one,
independent event, compound events
include two or more simple events

number of favorable outcomes
number of possible outcomes
Examples that use Probability:
(1) Dice, (2) Spinners, (3) Coins, (4) Deck
of Cards, (5) Evens/Odds, (6) Alphabet,
Etc.
P(event) =

0% 25% 50% 75% 100%
0 ¼ or .25 ½ 0r .5 ¾ or .75 1
Impossible Not Very Equally Likely Somewhat Certain
Likely Likely

Real World Example:
Best Buy is having an IPOD giveaway. They put
all the IPOD Shuffles in a bag. Customers may
choose an IPOD without looking at the color.
Inside the bag are 4 orange, 5 blue, 6 green,
and 5 pink IPODS. If Maria chooses one IPOD
at random and then her sister chooses one
IPOD at random, what is the probability they
will both choose an orange IPOD?

Real World Example:
Best Buy is having an IPOD giveaway. They put
all the IPOD Shuffles in a bag. Customers may
choose an IPOD without looking at the color.
Inside the bag are 4 orange, 5 blue, 6 green,
and 5 pink IPODS. If Maria chooses one IPOD
at random and then her sister chooses one
IPOD at random, what is the probability they
will both choose an orange IPOD?
P(orange,orange) = 4/20 x 3/19 = 3/95 or 3.2%

What are COMPOUND EVENTS?
- There are (2) types of compound
events:
(1) Independent Events – involves two or more
events in which the outcome of one event
DOES NOT affect the outcome of any
other events
Examples: roll dice, coin flip, problems with
replacement
P(A and B) = P(A) x P(B)

What are COMPOUND EVENTS?
- There are (2) types of compound
events:
(2) Dependent Events - involves two or more
DOES affect the outcome of any other
events
Examples: deck of cards, selecting item from
container, problems without replacement
P(A and B) = P(A) x P(B following A)

Example 1: Roll a dice.
What is the probability of rolling back to
back sixes?
P(6,then 6) =

back sixes?
1 1 1
6 6 36
P(6,then 6) = x =
1 1
1 2
1 3
1 4
1 5
1 6
2 1
2 2
2 3
2 4
2 5
2 6
3 1
3 2
3 3
3 4
3 5
3 6
4 1
4 2
4 3
4 4
4 5
4 6
5 1
5 2
5 3
5 4
5 5
5 6
6 1
6 2
6 3
6 4
6 5
6 6

back evens?
P(even,then even) =

back evens?
3 3 9 1
6 6 36 4
P(even,then even) = x = =
1 1
1 2
1 3
1 4
1 5
1 6
2 1
2 2
2 3
2 4
2 5
2 6
3 1
3 2
3 3
3 4
3 5
3 6
4 1
4 2
4 3
4 4
4 5
4 6
5 1
5 2
5 3
5 4
5 5
5 6
6 1
6 2
6 3
6 4
6 5
6 6

Example 3: Flip a coin.
What is the probability of flipping back
to back heads?
P(head,then head) =

Example 3: Flip a coin.
What is the probability of flipping back
to back heads?
Flip 1:
Flip 2:
Outcomes: TT TH HT HH
P(head,then head) = ½ x ½ = ¼

Example 4a: Deck of Cards.
What is the probability of drawing 2
hearts (without replacement)?
Hint: (1) how many cards are in a deck
(2) how many hearts are in a deck
(3) if you draw a heart how many card are left
and how many of those cads are hearts

Example 4: Deck of Cards.

Example 4a: Deck of Cards.
hearts (without replacement)?
Hint: (1) how many cards are in a deck (13)
(2) how many hearts are in a deck (52)
and how many of those cads are hearts (12 and 51)
13 12 1
52 51 17
P(heart,then heart) = x =

Example 4b: Deck of Cards.
hearts (with replacement)?
Hint: (1) how many cards are in a deck
(2) how many hearts are in a deck
and how many of those cads are hearts
P(heart,then heart) =

Example 4b: Deck of Cards.
hearts (with replacement)?
Hint: (1) how many cards are in a deck (13)
(2) how many hearts are in a deck (52)
and how many of those cads are hearts (13 and 52)
13 13 1
52 52 16
P(heart,then heart) = x =

Guided Practice: Questions.
(1) Wyatt has four $1 bills in his wallet and three
$10 bills in his wallet. What is the probability he
will reach into his wallet twice and pull out a $10
bill each time? (Assume he does replace the first
bill)
(2) A bag contains 3 green and 2 purple marbles.
What is the probability of drawing two purple
marbles in a row from the bag if the first marble
is not replaced?

Guided Practice: Answers.
(1) $1 $1 $1 $1 $10 $10 $10
3 3 9
7 7 49
(2)
P(purple,then purple) = 2/5 x 1/4 = 2/20 = 1/10
Probability of Compound
Events
P($10,then $10) = x =

Independent Practice: Questions.
(1) Wyatt has four $1 bills in his wallet and three
$10 bills in his wallet. What is the probability he
will reach into his wallet twice and pull out a $1
bill each time? (Assume he does not replace the
first bill)
(2) A bag contains 3 green and 2 purple marbles.
What is the probability of drawing two green
marbles in a row from the bag if the first marble
is replaced?
Events

Independent Practice: Answers.
(1) $1 $1 $1 $1 $10 $10 $10
4 3 12 2
7 6 42 7
(2)
P(purple,then purple) = 2/5 x 2/5 = 4/25
Events
P($1,then $1) = x = =

Summary: The difference between
simple and compound events:
(1) simple event – a specific outcome
or type of outcome.
(2) compound event – events which
consist of two or more simple events.

Summary: The difference between
independent and dependent events:
(1) independent event – two or more simple
DOES NOT affect the outcome of other
event(s)
(2) dependent event – two or more simple
DOES affect the outcome of other event(s)
Events

Real World Example:
Joanna had 3 roses, 4 tulips, and 1 carnation in
a vase. She randomly selected one flower,
took a photo of it, and put it back. She then
repeated the steps. What is the probability
that she selected a rose both times?
3 3 9
8 8 64
P(rose,then rose) = x =

Homework:

02_Probability of Compoujkjnd Events.ppt

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