Algebra 1 Common Core Student Edition, Grade 8-9

You can use experim ental probability to m ake a prediction. Predictions are n o t exact, so

ro u n d your results.

Pr o b l em 5 Using Experim ental Probability

Pets You ask 500 randomly selected h ousehold s in your town if they have a dog.

Of the 500 households, 197 respond that they do have a dog. If your town has

24,800 households, about how m any h ousehold s are likely to have a dog?

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• 197 of 500 respondents own a dog


• Your town has 24,800 households

Need

Likely number of

households that own

a dog

if e n

Find the experimental probability that a

household owns a dog. Then multiply it by

the total number of households.

n u m b e r of re sp o n d en ts th a t own a dog _ 197 _

P (o w n d o g ) n u m b e r of ho u seh o ld s surveyed 500 °-394

h o useholds w ith dog = P (ow n dog) • total n u m b e r of h o useholds

= 0.394 • 24,800 Substitute.

= 9 7 7 1 .2 Simplify.

It is likely th a t approxim ately 9770 h o useholds in your tow n own a dog.

Go t It? 5. A m anufacturer inspects 700 light bulbs an d finds th at 692 of th e light bulbs

work. There are ab o u t 35,400 light bulbs in th e m anufacturer's w arehouse.

About how m any of th e light bulbs in th e w arehouse are likely to work?

Lesso n Ch eck
Do yo u k n o w H OW?
Find the theoretical probability of each event w hen
rolling a num ber cube.

1. P ( 4)


2. P(less th a n 3)


3. P(not 3)


4. P (n o t greater th a n 4)


5. W hat are the odds in favor of rolling a 4 on a
   number cube?


6. You toss a d art at a d artb o a rd 500 dm es. You hit
   the bull's-eye 80 times. W hat is th e experim ental
   probability that you hit the bull's-eye?

Do yo u UN DERSTAN D? @ PRAOTCES

7. Vocabulary W hat is th e difference betw een
   theoretical probability and experim ental probability?


8. Error Analysis Eric calculated the probability
   of getting a n u m b e r less th a n 3 w h en random ly
   choosing an integer from 1 to 10. D escribe and
   correct his error.

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9. Open-Ended D escribe a real-w orld situation in
   w hich one event is nearly certain to occur and
   an o th er event is highly unlikely.

772 Ch ap t er 12 Dat a An al ysi s an d Pr o b ab i l i t y