Download 12.4 Multiplying Probabilities

§12.4 Multiplying
Probabilities
Algebra II Honors
Probability
of two
independent events, A and
B, both occurring is
P(A and B) = P(A) · P(B)
Example 1:
Sam has 9 dimes and 7
pennies in his pocket.
A) P(one penny)
B) P(one dime)
Example 1 cont..
Sam has 9 dimes and 7
pennies in his pocket.
Suppose he selects on coin,
puts I back, and then selects
another coin. Find the
probability that he selects on
dime followed by one penny.
Example 2: Dice
1. Find the probablity that one die
rolls a:
A) P(5)
B) P(1)
C) P( even number)
Example 2 cont…:
When three dice are rolled
what is the probability that
the first two dice roll a 5 and
the third die rolls an even
number?
If
two events, A and B, are
dependent then the
probability of both
occurring is
P(A and B) = P(A) · P(B following A)
Example 3:
Sam has 9 dimes and 7
pennies in his pocket. If Sam
selects two coins from his
pocket, one at a time, what is
the probability that both
coins are pennies?
Example 4:
Three cards are drawn from a
deck of cards without
replacement. What is the
probability of drawing a
heart, a heart, and a spade in
that order?
Homework
 HW
# 30
 Page 706
 12-35 all, 53-61 all