THINK AND DISCUSS
rl. Explain two ways to solve the proportion
f : f.
2. How could you show that the answer to Example 5A is reasonable?
3, GET ORGANIZED Copy and complete
the graphic organizer. In each box, write
an example ol each use of ratios.
flo€
Grade 8 Obi.
1,2,6
Grades 9-11 0bi. 1,2,8, 10
GUIDED PRACTICE
1. Vocabulary \Mhat does it mean when two ratios form a proportion?
I AMPLE
'l
2. The ratio of the sale price of a jacket to the original price
$64. \.44rat is the sale
p.114
price?
is 3 :4. The original price is
I
3. Chemistry
IAMPLE
L
are there?
2:
Find each unit rate.
p.114
I AMPLE
The ratio of hydrogen atoms to oxygen atoms in water is 2: 1. If an
amount of water contains 341 trillion atoms of oxygen, how many hydrogen atoms
4.
A computer's fan rotates 2000 times in 40 seconds.
5.
TWelve cows produce224,9BB pounds of milk.
L
6.
A yellow jacket can fly 4.5 meters in 9 seconds.
3r
7. Lydia wrote
+|VaZes of her science report in one hour. \.Vhat was her writing rate in
pages per minute?
p.115
A model airplane flies 1B feet in 2 seconds. \Alhat is the airplane's speed in miles per
hour? Round your answer to the nearest hundredth.
L,
T
AMPLE
p.116
*:
A vehicle uses 1 tablespoon of gasoline to drive 125 yards. How many miles can the
vehicle travel per gallon? Round your answer to the nearest mile, (Hint: There are
256 tablespoons in a gallon.)
Solve each proportion.
',0.2-+
11.
L:L
'12.
',r.f+:t
14.
-1 :3
15.
16.
7
x
17.
35
52d
3t
s-2
7
18.
b3
42
3 _s-2
t4 2I
10 52
h13
2-6 Rates, Ratios, and Proportions
117
19. Archaeology Stonehenge IIin
Hunt, Texas, is a scale model of the
ancient construction in Wiltshire,
England. The scale of the model
to the original is 3:5. The Altar
Stone of the original construction
is 4.9 meters tall. Write and solve a
proportion to find the height of the
model of the Altar Stone'
Alfred Sheppard, one of the builders of Stonehenge
PRAGTIGE AND PROBLEM SOLVING
height of a full-size
is the height of a full-size ficus?
ficus tree is 1:9. The bonsai ficusls 6 inches tall. !\rhat
20. Gardening The ratio of the height of
For
Exercises
See
a bonsai ficus tree to the
Example
20-21
22-23
24-25
I
76-37
4
38
5
21. ManufacturingAtonefactory,theratioofdefectivelightbulbsproducedto
2
totallightbulbsproducedisabout3:500.Howmanylightbulbsareexpectedtobe
3
defective when 12,000 are Produced?
Find each unit rate.
22. Four gallons of gasoline weigh 25 pounds'
23. Fifteen ounces of gold cost $6058'50'
Skills Practice P. 57
Application Practice P. S29
is this rate c '
The tropical giant bamboo can grow 11.9 feet in 3 days''what
nearest hundredth, and shor"'
growth in inches per rrJurt Round yorfi u**"r to the
that Your answer is reasonable'
24. Biology
25.TransportationThemaximumspeedoftheTupolevTu.l44airlineris694m/s.
\.Vhat is this speed in kilometers per hour?
Solve each ProPortion.
,u.
30.
34.
t =,
_]92
615
an
st
,r.? :- 4v
28.
6
tr. ? q-4
32.
35.
o
;
5
x+I
36.
z-5
h6
x 7.5
820
3x
5 100
,r.+: b+7
20
rr. *:13
n-5
rr.
20
#:
mite as seen under
Science The image shows a dust
Qgg.
'
u microscope. The scale of the drawing to the dust
mite is 100:1. Use a ruler to measure the length of
the dust mite in the image in millimeters' lVhat is the
actual length of the dust mite?
tgg.
ChaPter
60
U.S. dollars for 50 euro. How many U'S' dollars were
70 euro worth that day? Show that your answer is
reasonable'
*+0.
118
Finance On a certain day the exchange rate was
2 Equations
Environmental Science An environmental
scientist wants to estimate the number of carp in a
pond. He captures 100 carp, tags all of them, and
releases them. A week later' he captures 85 carp
and records how many have tags' His results are
shown in the table. Write and solve a proportion
to estimate the number of carp in the pond'
20
65