7th Grade Math

R22 Selected Answers and Solutions

Selected Answers and Solutions

25. Sample answer: The Crazy Horse statue is
    about twice as tall as the Motherland statue.


26. yes; 500

Chapter 8 Probability and

Predictions

Page 428 Chapter 8 Are You Ready?

1. 105 3. 52 5. 360 7. 5,040 9. 5 11. 4


2. 315 songs 15.^1 6 17. ^13

Pages 431–434 Lesson 8-1A

1. 81 , 0.125, 12.5% 3. ^18 , 0.125, 12.5%
   55 12 red + 6 orange = 18 possibilities out of
   30 marbles. So, 3018 simplifi es to equal ^35.
   7.^2330 9. 1 11. 201 , 0.05, 5% 13. _ 103 , 0.3, 30%


2. 2019 , 0.95, 95% 17. ^27 19. 61 21. ^57

2323 Since you are fi nding the probability the

student is NOT in Room 10, fi nd the total number

students in the other rooms. 24 + 20 + 14 + 16 =

74 students in the favorable outcomes group.

Add in the Room 10 number to fi nd the total

number of students is 84. P(not Room 10) = _ 8474

or _^3742

25. 60% 27. about 70% 29. Sample answer: The
    complementary event is the chance of no rain. Its
    probability is 60%.
    3131 There is one favorable outcome, and 5 total
    outcomes. Therefore, the probability that any given
    song would be hip-hop is _^15.


26. Sample answer: There are currently 6 + 4 + 8
    or 18 marbles in the bag. A total of 27 - 18 or
    9 marbles should be added to the bag. To do so
    without changing the probability of randomly
    selecting one marble of each color, add 3 red
    marbles, 2 blue marbles, and 4 green marbles.
    Then, P(red) = 279 or ^13 , P(blue) = 276 or ^29 , and
    P(green) = 2712 or 94 35. C 37. B 39a. ^14 39b. ^25
    39c. _^12

Pages 436–439 Lesson 8-1B

11 Sample answer:

H

H

T

T

H

T

H, H

H, T

T, H

T, T

$PJO
 $PJO


4BNQMF

Write heads. Show 4QBDF

that it leads to heads

and tails. Repeat this

for tails. The tree

diagram is shown.

3. Sample answer:

IBN

IBN


SZF

IBN


XIJUF

IBN


TPVSEPVHI

UVSLFZ


SZF

UVSLFZ


XIJUF

UVSLFZ


TPVSEPVHI

SZF

XIJUF

TPVSEPVHI

SZF

XIJUF

TPVSEPVHI

UVSLFZ

.FBU #SFBE 4BNQMF
4QBDF

5.

heads

tails

Coin Number Sample Space

1 2 3 4 5 1 2 3 4 5

heads, 1

heads, 2

heads, 3

heads, 4

heads, 5

tails, 1

tails, 2

tails, 3

tails, 4

tails, 5

7.

purple

green

black

silver

10

18

21

24

10

18

21

24

10

18

21

24

10

18

21

24

10

18

21

24

10

18

21

24

10

18

21

24

10

18

21

24

Color Speeds Sample Space

purple, 10-speed

purple, 18-speed

purple, 21-speed

purple, 24-speed

green, 10-speed

green, 18-speed

green, 21-speed

green, 24-speed

black, 10-speed

black, 18-speed

black, 21-speed

black, 24-speed

silver, 10-speed

silver, 18-speed

silver, 21-speed

silver, 24-speed

R01_R42_EM_SelAns_895130.indd R22 1/18/10 9:51 AM