Download Find Probability

Over Lesson 13–5
How many countries won between 1
and 10 medals?
A. 18
C.
12
B. 16
D.
10
How many countries won medals in
the 1998 Winter Olympics?
A. 32
B.
28
A.
C. 24
D.
10
Which country won the
B.
greatest number of medals?
C.
A. USA
B.
China
C. Canada
D.
cannot be determined
D.
A
B
C
D
You have already simplified ratios.
(Lesson 6–1)
• Find the probability of simple events.
• Predict the actions of a larger group.
• outcomes
Possible result of a probability experiment
• simple event
One outcome or a collection of outcomes.
• probability The ratio of the number of ways a certain event can
occur to the total number of possible outcomes
• sample space The set of all possible outcomes
• random Outcomes occur at random if each outcome is equally
likely to occur (it is not fixed or has been manipulated)
• theoretical probability What should occur in a probability
• experimental
probability
experiment
What actually occurs in a probability experiment
Find Probability
Suppose a number cube is rolled. What is the
probability of rolling a 4 or a 5?
There are 2 numbers on the number cube that are
a 4 or a 5: 4 and 5.
There are 6 possible outcomes: 1, 2, 3, 4, 5, and 6.
Answer:
Suppose a number cube is rolled. What is the
probability of rolling a number that is divisible by 3?
A. AnsA
B. AnsB
C. AnsC
D. AnsD
A.
B.
C.
D.
A
B
C
D
Find Probability
Suppose that two number cubes are rolled. Find the
probability of rolling two identical numbers.
Make a table showing the sample space when rolling
two number cubes.
Find Probability
There are 6 outcomes in which the two numbers
are identical.
Answer:
Suppose that two number cubes are rolled. Find the
probability of rolling two numbers whose sum is 8.
A.
B.
C.
D.
A.
B.
C.
D.
A
B
C
D
Find Experimental Probability
A coin was tossed 40 times and heads came up
18 times. Find the experimental probability of
getting tails for this experiment. Then compare the
experimental probability with the theoretical
probability.
Find Experimental Probability
Answer: So, tossing tails in the experiment occurred
more often than expected.
BASKETBALL Brian is shooting baskets with a
basketball. He makes 13 shots and misses 9 shots.
Determine the experimental probability of Brian
making a shot.
A.
B.
C.
D.
A.
B.
C.
D.
A
B
C
D
Make a Prediction
SPORTS Miss Newman surveyed her class to see
which sports they preferred watching. 44%
preferred football, 28% basketball, 20% soccer, and
8% tennis. Out of 560 students in the entire school,
how many would you expect to say they prefer
watching basketball?
Understand
You know that 28% prefer basketball.
You need to find how many students
out of 560 prefer basketball.
Plan
Use the percent proportion to find
28% of 560.
Make a Prediction
Solve
part
whole
The percent is 28% and 560 is the
whole. Let a represent the part.
percent
Make a Prediction
Answer: You can expect about 157 students to say they
prefer watching basketball.
Check
Estimate: 28% is about 25%.
25% of 600 is 150.
So, 157 is reasonable.
COLORS The students in an art class were surveyed
about their favorite color. 32% preferred blue, 29%
preferred red, 23% preferred yellow, and 16%
preferred green. Out of 450 students in the entire
school, how many would you expect to say they
prefer red?
A. about 6
B. 29
C. about 131
D. 144
A.
B.
C.
D.
A
B
C
D