Simple Theoretical Probability Notes
69B
_________________ probability consists of __________ event. It is calculated by dividing the
number of outcomes over the number of ____________________ outcomes.
Guided Practice:
Example #1: Bobby rolls a six-sided die, what is the probability (P) that he will roll a two?
# of Outcomes
# of Possible Outcomes
Can you simplify?
Example #2: June wants to read a Shakespearean comedy. Shakespeare wrote 6 comedies
and 12 tragedies. What is the probability (P) that she will select a comedy?
# of Outcomes
# of Possible Outcomes
Can you simplify?
Example #3: Carly randomly chooses a card from a deck of cards. What is the probability (P)
that she will select a spade?
# of Outcomes
# of Possible Outcomes
Can you simplify?
You Try:
1) The faces of a fair 6-sided cube are numbered 1
through 6. The number cube is rolled. What is
the probability that it will land on an even
number?
2) A standard six-sided number cube is rolled. What
is the probability a 3 or a 5 will land face up?
Simple Theoretical Probability Practice
1) The pieces of candy in Paul’s bag of candy have
the following colors:
40% red
30% blue
2) The following number cards are in a lottery box.
30% yellow
If Paul’s friends selected a piece of candy at
random today, what is the probability that he will
select a red piece of candy?
3) A bag of marbles contains 9 red, 7 purple, 6 blue
and 3 yellow marbles. If pulling one marble out
of the bag, what is the probability of choosing a
purple marble?
A number can be drawn at random from the
lottery box. What is the probability of drawing a
10, 12, or 14?
4) The circle consists of the numbers 1, 3, 4, 5.
What is the probability of selecting an even
number?
5) Benny has a basket of 5 red balls, 3 yellow balls,
and 2 green balls. He will pick one ball at
random. What is the probability that the next
ball he randomly chooses will be red or green?
6) Ronnie is playing darts with his friends. What is
the probability that his dart will land in a shaded
square.
7) In Mr. Brown’s classroom, 40% of the students
are boys. If Mr. Brown chooses a student to
answer a question in his classroom, what is the
probability that the student he chooses is a boy?
8) Jeff is working on shooting free throws in
basketball. Of the 72 shots he has tries, he has
made 54. What is the probability Jeff’s next shot
will go in based on his rate so far?
a)
1
b)
1
c)
3
d)
2
2
4
4
3
Compound Theoretical Probability Notes
A _________________________to determine the likelihood of two ______________________
events occurring at the _______________________________.
***Events can be classified as independent or dependent events.
•
Independent Events are events in which the result of _________________ event
_________________________ affect the result of the ___________________event.
o Example: Suzie selects two chips from a bag of red and blue chips.
Selecting one chip and ______________________ it before the next selection.
•
Dependent Events are events in which the result of the first event ________________ the results of
the event _________________________________.
o Example: Suzie selects two chips from a bag of red and blue chips.
Selecting one chip and ______________________ it before the next selection.
Determine if the following problems are simple, independent, or dependent theoretical probability.
1) On a shelf there are 60 novels and 20 poetry books. What is the
probability that Person A chooses a novel and walks away with it Simple Independent Dependent
and then Person B walks up shortly after and picks another
novel?
2) What is the probability of getting a 7 after rolling a single
Simple Independent Dependent
number cube number 1 to 6?
3) Numbers 1 to 20 are placed in a bag. Without replacing the first
number, what is the probability that the first number drawn will
be odd and the second will be even?
Simple
Independent
Dependent
4) Diamond is playing a game. In the game she has to spin a spinner
that is divided into equal sections of orange, red, purple, and
pink. What is the probability that on her first spin she will land
on pink and then red on her second spin?
Simple
Independent
Dependent
5) A deck of playing cards contains 52 cards. What is the probability
of pulling out a King of Diamonds and without replacing it, then
an Ace of Spades?
Simple
Independent
Dependent
6) What is the probability of rolling a 4 on a number cube and
pulling a red marble out of a bag that contain 3 red, 2 black, and
5 yellow marbles?
Simple
Independent
Dependent
Simple
Independent
Dependent
7) Spinning an even number on a spinner numbered from 1 to 10
Compound Theoretical Probability Practice
8) Diamond is playing a game. In the game she has
to spin a spinner that is divided into equal
sections of orange, red, purple, and pink. What is
the probability that on her first spin she will land
on pink and then red on her second spin?
9) On a shelf there are 60 novels and 20 poetry
books. What is the probability that Person A
chooses a novel and walks away with it and then
Person B walks up shortly after and picks
another novel?
10) Numbers 1 to 20 are placed in a bag. Without
replacing the first number, what is the
probability that the first number drawn will be
odd and the second will be even?
11) What is the probability of rolling a 4 on a number
cube and pulling a red marble out of a bag that
contain 3 red, 2 black, and 5 yellow marbles?
12) A spinner is divided into 8 equal sections as
shown.
13) You have a bag of 17 colored chips.
Four are blue, 6 are green, 2 are red, and the others
are yellow. What is the probability of drawing a blue
chip, replacing it, and then drawing a yellow chip?
What is the probability that the spinner will land on
a section that is an integer and then land on a
section that is a perfect square?
14) What is the probability of rolling a 3 on a 6-sided
number cube and then NOT rolling a 3 on a 6sided number cube?
15) Using the spinner from #12, what is the
probability of spinning a natural number then an
integer?