1. Do Now
Write the equivalent percent.
Write the equivalent fraction.
7. 50%
30%
25%
20% 4.
10% 5.
40% 6.
35%
Write the equivalent decimal.
0.5
0.2
0.9

2. An experiment is an activity involving chance
An experiment is an activity involving chance. Each repetition or observation of an experiment is a trial, and each possible result is an outcome. The sample space of an experiment is the set of all possible outcomes.

3. Example 1: Identifying Sample Spaces and Outcomes
Identify the sample space and the outcome shown for each experiment.
A. Rolling a number cube
Sample space:{1, 2, 3, 4, 5, 6}
Outcome shown: 4
B. Spinning a spinner
Sample space:{red, green, orange, purple}
Outcome shown: green

4. An event is an outcome or set of outcomes in an experiment.
Probability is the measure of how likely an event is to occur. Probabilities are written as fractions or decimals from 0 to 1, or as percents from 0% to 100%.

5. As likely as not Impossible Certain Unlikely Likely 0% 50% 100%
Events with a probability of 0% never happen.
50%
Events with a probability of 50% have the same chance of happening as not.
100%
Events with a probability of 100% always happen.

6. You can estimate the probability of an event by performing an experiment.
The experimental probability of an event is the ratio of the number of times the event occurs to the number of trials. The more trials performed, the more accurate the estimate will be.

8. Example 2A: Finding Experimental Probability
An experiment consists of spinning a spinner. Use the results in the table to find the experimental probability of the event.
Outcome
Frequency
Green 15
Orange 10
Purple 8
Pink 7
Spinner lands on orange

9. Example 2B: Finding Experimental Probability
An experiment consists of spinning a spinner. Use the results in the table to find the experimental probability of the event.
Outcome
Frequency
Green 15
Orange 10
Purple 8
Pink 7
Spinner does not land on green

10. Example 3A: Try It Now
An experiment consists of spinning a spinner. Use the results in the table to find the experimental probability of each event.
Outcome
Frequency
Red 7
Blue 8
Green 5
Spinner lands on red

11. Example 3B: Try It Now
An experiment consists of spinning a spinner. Use the results in the table to find the experimental probability of each event.
Outcome
Frequency
Red 7
Blue 8
Green 5
Spinner does not land on red

12. You can use experimental probability to make predictions.
A prediction is an estimate or guess about something that has not yet happened.

13. Example 4A: Quality Control Application
A manufacturer inspects 500 strollers and finds that 498 have no defects.
What is the experimental probability that a stroller chosen at random has no defects?
Find the experimental probability that a stroller has no defects.
= 99.6%
The experimental probability that a stroller has no defects is 99.6%.

14. Example 4B: Manufacturing Application
A manufacturer inspects 500 strollers and finds that 498 have no defects.
The manufacturer shipped 3500 strollers to a distribution center. Predict the number of strollers that are likely to have no defects.
Find 99.6% of 3500.
0.996(3500) = 3486
The prediction is that 3486 strollers will have no defects.

15. Example 5A: Try It Now
A manufacturer inspects 1500 electric toothbrush motors and finds 1497 have no defects.
What is the experimental probability that a motor chosen at random will have no defects?
Find the experimental probability that a motor has no defects.
= 99.8%

16. Example 5B: Try It Now
A manufacturer inspects 1500 electric toothbrush motors and finds 1497 have no defects.
There are 35,000 motors in a warehouse. Predict the number of motors that are likely to have no defects.
Find 99.8% of 35,000.
0.998(35000) = 34930
The prediction is that 34,930 motors will have no defects.

17. Points to Remember
Experimental probability =
Probability can be expressed as a fraction, decimal, or percent.

18. Lesson Quiz: Part I
1. Identify the sample space and the outcome shown for selecting a marble.
Sample space: {red, green, yellow}
Outcome shown: red

19. Lesson Quiz: Part II
2. An experiment consists of spinning a spinner. Use the results in the table to find the experimental probability of landing on blue.
Outcome
Frequency
Red 9
Blue 6
Yellow 5

20. Lesson Quiz: Part III
3. The neighbors’ dog barked at Tana the last 4 out of 5 times she walked by their house.
a. What is the experimental probability that the dog barks at Tana when she walks past the house?
80%
b. Predict the number of times the dog will bark at Tana if she walks past the house 45 times. 36