Lesson 7-4 Pages 304-308
Scale Drawings
Lesson Check 7-3
What you will learn!
How to solve problems
involving scale drawings.
Scale drawing
Scale
Scale factor
Scale model
What you really need to know!
A scale drawing
represents something
that is too large or too
small to be drawn at
actual size.
What you really need to know!
A scale model can
be used to represent
something that is too
large or too small for
an actual-size model.
What you really need to know!
The scale gives the
relationship between
the drawing/model
measure and the
actual measure.
Example 1:
On the map,
the distance
between
Portland and
Olympia is
about 1 7/8
inches. What
is the actual
distance?
3
7
in 1 in 3
7
m  1 x 25
8  8
8
8
25mi
m
From Lesson 6-5:
Solving Equations
involving Fractions!
3
m  46.875
7 8
m  46 
8
8 3
125 miles
Example 2:
On the blueprint of
a new house, onequarter inch
represents 2 ½
feet. If the length
of a bedroom on
the blueprint is 1 ½
inches, what is the
actual length of the
room?
1
1
in 1 in
4
2

1
m
2 ft
2
1
1 1
m  1 x2
4
2 2
1
3
3 4
m3 m3 
4 1
4
4
15 feet
Example 3:
Find the scale factor of
a blueprint if the scale
is ½ inch = 3 feet.
1
1
inch
inch
2
2

3 feet 36inches
1
inch
2
1
inch
1
2
 

36inches 2 72inches 72
Example 4:
A model is being created from a
picture frame which has a width
of 4 ¾ inches. If the scale to be
used is 8 inches = 1 inch, what is
the length of the model?
Important Knowledge:
Scales are always given
with the real item as the
denominator.
8
L

1 43
4
8
L

3
1 4 3 1 L  8  4
4
4
L  38
38 inches
Page 306
Guided Practice
#’s 3-8
Read:
Pages 304-306
with someone at
home and study
examples!
Homework: Page 307-308
#’s 9-15, 17-25, 28-38
Lesson Check 7-4
Page
581
Lesson 7-4
Lesson Check 7-4
Prepare for Mid-Test!
Page
310
#’s 1-20
Lesson Check 7-4
Homework: Page 307-308
#’s 9-15, 17,18,
21-23, 28-38
Lesson Check 7-4
A rate is a ratio that compares
quantities with different labels.
A unit rate is a rate that is simplified so
that the denominator is 1.
Rate
Unit Rate
225mi
3hrs
75mi
1hr
A rate is a ratio that
compares quantities with
different units, such as
16feet/8seconds.
A unit rate is a rate that is
simplified so that it has a
denominator of 1 unit, such
as 2feet/1second.
In a proportion, the cross
product is the product of the
numerator of one ratio and
the denominator of the other
ratio.
In a proportion, a cross product is the
product of the numerator of one ratio
and the denominator of the other ratio.
8 2

12 3
8 x 3 = 24
12 x 2 = 24