Download Probability

Name ———————————————————————
SECTION
7
Date ————————————
Probability
Lesson 6: Probability of a Compound Event
A compound event is an event that consists of more than one outcome.
EXAMPLE 1
Amy picks a marble and spins the spinner.
What is the probability that she picks the
striped marble and spins a 3?
1
2
3
One Method: Use a table to organize all
the possible outcomes. There are 12
outcomes, 2 of which have striped and 3.
So, the probability that Amy picks the
2
Black
White
Striped
1
striped marble and spins a 3 is }
5 }6.
12
Another Method: Multiply probabilities. The
events pick a striped marble and spin a 3 are
independent events, so you can use the
formula
P(A and B) 5 P(A) • P(B).
1
2
3
3
B1 B2 B3 B3
W1 W2 W3 W3
S1 S2 S3 S3
HINT
Compound probability is
equal to the product of the
probabilities of each event.
1
1
1
P(striped and 3) 5 P(striped) • P(3) 5 }3 • }2 5}6
A bag contains 8 marbles—5 red and 3 black. What is the probability of choosing
a red marble and then choosing a black marble?
If the first marble is replaced,
the events are independent.
If the first marble is not replaced,
the events are dependent.
P(red) • P(black) 5
P(red) • P(black given red) 5
5 3
15
} • } 5 } ø 23%
8 8
64
} • } 5 } ø27%
5
8
3
7
15
56
B
7 marbles left in the bag after the first marble is chosen
7. PROBABILITY
6. Compound Events
Copyright © by McDougal Littell, a division of Houghton Mifflin Company.
EXAMPLE 2
3
Practice: First Try
A jar contains 5 marbles—2 green, 2 blue, and 1 yellow. Jenny rolls
a 1-6 number cube and picks a marble. Use a table to organize all
possible outcomes and write your answers as fractions.
1. What is the probability of rolling a 6 and picking a yellow marble?
2. What is the probability of rolling an odd number and picking a blue marble?
A bag contains 10 tiles—3 green, 1 white, and 6 red.
3. Find the probability of picking white, replacing it, and then picking green.
4. Find the probability of picking white, not replacing it, and then picking green.
5. Find the probability of picking red, not replacing it, and then picking red again.
McDougal Littell Middle School Math
Remediation Book Lesson 7.6
231
Name ———————————————————————
Date ————————————
Practice: Second Try
Henry rolls a 1-6 number cube and spins the spinner.
1. Draw a table to show all possible outcomes.
C
A
1
A
2. What is the probability of rolling a 3 and spinning
an A?
B
2
3
C
A
3. What is the probability of rolling a number less than 6
and spinning a B?
4. What is the probability of rolling an odd number and spinning a C?
Joy is drawing random cards from a standard deck of 52 cards.
5. What is the probability of drawing a Heart, replacing it, and then drawing
a Diamond?
6. What is the probability of drawing a red card, not replacing it, and then
drawing a black card?
7. What is the probability of drawing the Jack of Hearts, not replacing it, and
then drawing the Queen of Hearts?
8. What is the probability of drawing an Ace, replacing it, and then drawing
a King?
9. You participate in a game. You draw one random card
from a standard deck of 52 cards. If you draw a King,
you get to spin the spinner one time. What is the
probability of winning a trip to Disney World, written
as both a fraction and a percent?
Free trip to
Disney
World
10. The face cards in a standard deck are Jack, Queen, and
King. Suppose you could win a Disney World trip by
drawing 2 face cards without replacement. (There is no
spinner in this game.) Would you have a better chance to
win the Disney World trip in this game? Explain your answer.
2 free
movie
tickets
Puzzle
Amy rolls two 1-6 number cubes. Every time she rolls, her two
numbers match. Brett rolls two 1-6 number cubes. Every time
he rolls, his sum is 7.
Shade in all possible outcomes for Amy and Brett on the grid to
find the letter.
1
1
2
3
4
5
6
232
2 free
movie
tickets
LOSE
McDougal Littell Middle School Math
Remediation Book Lesson 7.6
2
3
4
5
6
Copyright © by McDougal Littell, a division of Houghton Mifflin Company.
7. PROBABILITY
6. Compound Events
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