7th Grade Math

Test PracticeT

Compound Events

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30. Juan is holding four straws of different
    lengths. He has asked four friends to
    each randomly pick a straw. Milo picks
    first, and keeps the second longest straw.
    What is the probability that Felipe will
    get the longest straw if he picks
    second?
    A. ^14 C. ^13

B. ^12 D. ^15

31. The spinner is spun
    $5
    off

$25

off

$10

off

$10

off

$5

off

$20

off

$10

off

$15

off

$5

$$$$

twice. What is the

probability that the

spinner will land on

a section for $10 off

and then $5 off?

F. _^38 H. _ 645

G. ^14 I. 323

32. The spinners are each spun once.

32

3 2

3 3

4 1

2

WHITE BLUE

RED RED

What is the probability of spinning

2 and white?

A. _ 161 C. _^25

B. ^14 D. ^35

33. A jar of beads contains 6 aqua beads and
    4 black beads. If two beads are selected
    at random, with replacement, what is
    the probability that both beads will be
    aqua?
    F. ^13 H. ^35

G. 259 I. 109

Sometimes two events cannot happen at the same time. For

example, when a coin is tossed, either heads or tails will turn up.

Tossing heads and tossing tails are examples of disjoint events,

or events that cannot happen at the same time. Disjoint events

are also called mutually exclusive events.

A number cube is rolled. What is the probability of rolling a

multiple of 3 or a 1?

P(multiple of 3 or 1) = _^36

So, the probability of rolling a multiple of 3 or a 1 is ^36 or ^12.

A number cube is rolled. Find each probability. Write as a fraction in

simplest form.

34. P(4 or 5) 35. P(3 or even number) 36. P(1 or multiple of 2)

There are three favorable outcomes: 1, 3, or 6.

There are 6 total outcomes.

Lesson 2B Compound Events 455

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