7th Grade Math

432 Probability and Predictions

= Step-by-Step Solutions begin on page R1.

Extra Practice begins on page EP2.

A set of 20 cards is numbered 1, 2, 3,... 20. Suppose you pick a card at

random without looking. Find the probability of each event. Write as a

fraction in simplest form, a decimal, and a percent.

Example 1

11. P(1) 12. P(3 or 13) 13. P(multiple of 3)


12. P(even number) 15. P(not 20) 16. P(not a factor of 10)

RAFFLE The table shows the number of students in Lunch Raffle

Room 8 24

Room 9 20

Room 10 10

Room 11 16

Room 12 14

seventh grade who entered the school drawing to win

lunch with the principal. Suppose that only one student

is randomly selected to win. Find the probability of

each event. Write as a fraction in simplest form.

Examples 2 and 3

17. P(Room 8) 18. P(Room 9)


18. P(Room 12) 20. P(Room 10)^


19. P(not Room 8) 22. P(Room 11)
    2323 P(not Room 10) 24. P(Room 10 or 11)


20. SOUP A cupboard contains 20 soup cans. Seven are tomato, 4 are cream
    of mushroom, 5 are chicken, and 4 are vegetable. If one can is chosen
    at random from the cupboard, what is the probability that it is neither
    cream of mushroom nor vegetable soup? Write as a percent.


21. VIDEOS In a drawing, one name is randomly chosen from a jar of 75 names
    to receive free video rentals for a month. If Enola entered her name 8 times,
    what is the probability that she is not chosen to receive the free rentals?
    Write as a fraction in simplest form.

B 27. PETS The graph shows the last

Dogs Cats Birds Snakes

10

15

5

0

Number Purchased

Gerbils

Type of Pet

9

14

(^325)
Pet Store
33 types of pets that were
purchased at a local pet store.
What is the probability that a
receipt chosen at random from
these sales would be for a cat
or dog? Express as a percent.

28. GAMES For a certain game, the
    probability of choosing a card
    with the number 13 is 0.008.
    What is the probability of not
    choosing card 13? Then describe the likelihood of the event occurring.


29. WEATHER The forecast for tomorrow says that there is a 40% chance of rain.
    Describe the complementary event and predict its probability.

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