Section 9.3 Experimental Probability 401

Exercises 7–18

EXAMPLE

Comparing Experimental and Theoretical Probabilities

3

The bar graph shows the results of rolling a number cube

50 times. What is the experimental probability of rolling an

odd number? How does this compare with the theoretical

probability of rolling an odd number?

Find the experimental probability of rolling a 1, 3, or 5.

The bar graph shows 10 ones, 8 threes, and 8 ﬁ ves.

So, an odd number was rolled 10 8 8 26 times in

a total of 50 rolls.

The experimental probability is

13

25

0.52 52%. The theoretical

probability is

1

2

0.5 50%. The experimental and theoretical

probabilities are similar.

3. In Example 3, what is the experimental probability of rolling a

number greater than 1? How does this compare with the

theoretical probability of rolling a number greater than 1?

Exercise 19

Times rolled

Rolling a Number Cube

6

8

10

0

2

4

12

123456

Number rolled

1. In Example 1, what is the experimental probability that your

next email is not junk?

2. At a clothing company, an inspector ﬁ nds

5 defective pairs in a shipment of 200 jeans.

a. What is the experimental probability of

a pair of jeans being defective?

b. About how many would you expect to be

defective in a shipment of 5000 pairs of jeans?

An odd number was rolled 26 times.

There was a total of 50 rolls.

Experimental Probability Theoretical Probability

P(event)

number of times the event occurs

total number of trials

P(event)

number of favorable outcomes

number of possible outcomes

P(odd)

26

50

P(odd)

3

6

13

25

1

2

There are 3 odd numbers.

There is a total of 6 numbers.