EXAMPLE 1 Using Theoretical Probability

Predict the number of times a coin will land heads up in 50 coin tosses. There are two equally likely outcomes when you toss the coin, heads or tails.

Coin Toss

=12

You can predict that , or 25, of the tosses will land heads up.

12

ANSWER

P(heads) Number of favorable outcomesNumber of possible outcomes=

EXAMPLE 2 Finding Experimental Probability

You roll a number cube 100 times. Your results are given in the table below. Find the experimental probability of rolling a 6.

P(rolling a 6)= 18100

Number of favorable outcomesTotal number of rolls

= 0.18 = 18%

The experimental probability of rolling a 6 is 18%.

ANSWER

EXAMPLE 3 Standardized Test Practice

SOLUTION

STEP 1

Find the experimental probability of a button being defective.

P(defective) =2

300 = 1150

EXAMPLE 3 Standardized Test Practice

STEP 2

Multiply the probability by the total number of buttons in the shipment and round to the nearest whole number.

1150 20,000 133

You could expect about 133 buttons in a shipment of 20,000 to be defective. The correct answer is C.

ANSWER

GUIDED PRACTICE for Examples 1, 2 and 3

Use the information given in Example 2. What is the experimental probability of rolling a number greater than 3? What is the theoretical probability of this event?

Number Cube1.

The experimental probability of rolling a number greater than 3 is 48%.

ANSWER

The theoretical probability of rolling a number greater than 3 is 50%.

GUIDED PRACTICE for Examples 1, 2 and 3

Use the information in Example 3. About how many buttons would you expect to be defective in a shipment of 25,000 buttons?

What If?2.

You could expect about 167 buttons in a shipment of 25,000 to be defective.

ANSWER