Target: Find and interpret

experimental and theoretical probabilities.

Write each percent as a fractionWrite each percent as a decimal.

1. 50%

2. 10%

3. 89%

Write each fraction as a percent.

4.

5.  

6. Juan flipped a coin 10 times and it landed heads 7 times. Write the ratio of number of times the coin landed heads to

total number of flips.

4

1

5

4

Probability: ◦ The measure of how likely it is an even will occur.

Outcome: ◦ One possible result from an experiment or probability event.

Event: ◦ A desired outcome or group of outcomes.

Theoretical Probability: ◦ The ratio of favorable outcomes to the number of possible outcomes.

total

favorable

Experimental Probability: ◦ The ratio of the number of times an event occurs to the total

number of trials.

Trial: A single act of performing an experiment.

Complement: Two probabilities whose sum is 1. Together they make up all the possible outcomes without repeating any outcomes.

outcomes possible ofnumber

outcomes favorable ofnumber P(event) event an ofy Probabilit

a. Find P(1 or 2) when rolling a number cube.

b. Find P(7) when rolling a number cube.

3

1

6

2

6) 5, 4, 3, 2, (1, outcomes possible ofnumber

2) (1, outcomes favorable ofnumber 2)or P(1

06

0

6) 5, 4, 3, 2, (1, outcomes possible ofnumber

(0) outcomes favorable ofnumber P(7)

trialsofnumber total

occursevent the timesofnumber P(event)

Use the spinner to write each probability as a fraction decimal and percent.

Kyle rolled a number cube 60 times. His results are shown in the table below.

a. Find Kyle’s experimental probability of rolling a 6.

b. Find Kyle’s experimental probability of not rolling a 6.

Number rolled 1 2 3 4 5 6

Frequency 8 12 6 15 4 15

4

1

60

15

trialsofnumber

rolled was6 a timesofnumber )6(P

4

3

60

45

(60) trialsofnumber

4)15612 (8 rollednot was6 a timesofnumber 6)P(not

Kyle rolled a number cube 60 times. His results are shown in the table below.

c. Find the theoretical probability of rolling a 6.

d. Find the theoretical probability of not rolling a 6.

Number rolled 1 2 3 4 5 6

Frequency 8 12 6 15 4 15

6

1

outcomes possible ofnumber

outomes favorable ofnumber P(6)

6

5

outcomes possible ofnumber

outcomes favorable ofnumber 6)P(not

Mr. Tibbets has a deck of cards numbered 1 through 20. The cards are

shuffled. One card is picked at random. Find each probability.

1. P(7)

2. P(odd number)

3. P(40)

4. Martha picked cards 40 times and picked a “7” four times.

a. What is the experimental probability Martha will pick a “7”?

b. Is Martha’s experimental probability greater than or less than the

theoretical probability of picking a “7”?

Your friend needed a coin to land “tails” to win a new shirt at the mall. The coin was tossed 15 times and never landed “tails”. She complained that the coin wasn’t fair. What do you think? Why?

Probability

Lesson 13