Academy Algebra II/Trig
14.3: Probability
HW: worksheet
Test: Thursday, 11/14
Probability

Theoretical probability that event A will occur:

When an experiment is performed, the
experimental probability of an event A is:
Find the probability of selecting the
following number from the numbers 1 – 50.
1.) a perfect square
2.) a factor of 150
Odds

The odds that event A will occur:
You randomly choose a marble from a bag
of 10 black, 8 red, 4 white, and 6 blue. Find
the indicated odds.
1.) in favor of choosing white
2.) against choosing red
A card is randomly selected from a standard
52-card deck. Find the probability of
drawing the given card.
1.) the king of diamonds
2.) a spade
3.) a red card
The results of rolling a 6-sided die is
shown. Find the experiment and
theoretical probability.
Roll
1
2
3
4
5
6
# of occurrances 27
22
18
26
27
30
1.) rolling an even #
2.) rolling a # less than 5
Compound Events
Or in probability means union.
 And in probability means intersection.

Union of Events: overlapping vs. disjoint
If they have nothing
in common there will
be nothing to
subtract.
A card is randomly drawn from a standard
deck of 52 cards. Find the probability of
drawing the indicated card.
1.) A heart or a diamond
2.) A spade or an even card
A card is randomly drawn from a standard
deck of 52 cards. Find the probability of
drawing the indicated card.
3.) A 6 or a 7
4.) An ace or a spade
A card is randomly drawn from a standard
deck of 52 cards. Find the probability of
drawing the indicated card.
5.) An ace and a spade
6.) A face card and a 4
Probability of the Complement of an Event
The event A, called the complement of event
A, consists of all outcomes that are not in A.
 The probability of the complement of A is

Independent vs. Dependent Events

Independent events: 2 events are independent
if the occurrences of one has no effect on the
other.

Dependent events: the occurrences of one
affects the occurrence of the other.
means the probability that B will
occur given that A has occurred (conditional
prob).
A hat contains 10 blue,4 red,& 6 white marbles.
1.) Find the probability of choosing a red, then a
white marble with replacement, then without
replacement.
A hat contains 10 blue,4 red,& 6 white marbles.
2.) Three marbles are chosen with replacement,
find the probability that they are not white.
Find the probability that at least one is white.
Find the probability of drawing the given cards
from a standard deck of 52 cards
(a) with replacement and
(b) without replacement.
1.) a heart, then a spade
2.) a king, then a queen
Find the probability of drawing the given cards
from a standard deck of 52 cards
(a) with replacement and
(b) without replacement.
3.) a 4, then a 3, then a 2
4.) a 10, then a 10, then another 10