Theoretical probability shows what should happen in an experiment.

Experimental probability shows what actually happened.

Experimental probability:P(event) = number of times event occurs total number of trials

Theoretical probability:P(A) = number of favorable outcomes

total number of possible outcomes

A bag contains three red marbles and three blue marbles.

P(red) = 3/6 =1/2 Theoretical (The result is based on the

possible outcomes)

Not in notes

Trial Red Blue

1 1

2 1

3 1

4 1

5 1

6 1

Total 2 4

Exp. Prob. 1/3 2/3

You draw a marble out of the bag, record the color, and replace the marble. After 6 draws, you record 2 red marbles

P(red)= 2/6 = 1/3 Experimental(The result is found by repeating

an experiment.)

Not in notes

1. P (heads) =________

2. P (tails) = ________

HEADS TAILS

llll llll llllllll

llll llll llll

Experimental

=_________________

=__________________

Theoretical

1535

2035

47

37

12

12

2

1

7

4

14

7

14

8Experimental - Theoretical

This is about 7%

1

14

7

3

2

1

14

6

14

7Tails?

1

14

4) P(4) = ______________

5) P(odd ) = __________

6) P(2 or 5) = __________

7) P(factor of 3) = _________

David rolled a number cube, with the numbers 1-6 on it. He recorded the results in the table below.

Number Outcomes

1 IIII2 III3 IIII4 IIII I5 II6 I

8) What is the difference between the experimental probability of rolling a 2 or 5, and the theoretical probability of rolling a 2 or 5?

1/6

10/20 = ½

5/20 = 1/4

8/20 = 2/5

1/3 – 1/4 = 4/12 – 3/12 = 1/12

6/20= 3/10

Experimental Theoretical

1/2

1/3

1/3

If a car factory checks 360 cars and 8 of them have defects, how many will have defects out of 1260?

P(defects) = 8

360=

1

45

1

45=

1260

X= = 281260 ÷ 45

9)

Essential Question

How are experimental and theoretical probability alike?

Date __________________________

probability shows what __________________in an experiment. probability shows what _________________.

Experimental probability:P(event) = ___________________________

Theoretical probability:P(A) = ______________________________

1. P (heads) =________

2. P (tails) = ________

HEADS TAILS

llll llll llllllll

llll llll llll

Experimental

=_________________

=__________________

Theoretical

Experimental - Theoretical

David rolled a number cube, with the numbers 1-6 on it. He recorded the results in the table below.

Number Outcomes

1 IIII2 III3 IIII4 IIII I5 II6 I

4) P(4) = ______________

5) P(odd ) = __________

6) P(2 or 5) = __________

7) P(factor of 3) = _________

What is the difference between the experimental probability of rolling a 2 or 5, and the theoretical probability of rolling a 2 or 5?

Experimental Theoretical

8)

If a car factory checks 360 cars and 8 of them have defects, how many will have defects out of 1260?

P(defects) =

9)

Essential Question

How are experimental and theoretical probability alike?