Page 211 - Math Course 1 (Book 1)

Understanding Scale Drawings

Mo. 6

Lesson 9
Let’s Begin

KEY CONCEPTS:
1. Use scale drawings. Find Actual Measurements
2. Construct scale drawings.
3. Construct scale drawings.
Example

MO. 6 - L9a MAP

A map has a scale of 1 inch = 8 miles. Two towns
Using Scale Drawings are 3.25 inches apart on the map. What is the
actual distance between the two towns?

Method 1 Use a proportion.
Vocabulary A-Z Let x represent the actual distance between the

Let us learn some vocabulary two towns. Write and solve a proportion.

map distance 1 inch = 3.5 inches map distance

actual distance 8 miles x miles actual distance
Scale Drawing

is determined by the ratio of a given length on the 1 • x = 8 • 3.25 Find the cross
drawing or model to its corresponding length on the products.
actual object.
x = 26 Simplify.
1 inch = 3 feet
The actual distance between
Answer the two towns is 26 miles.
1 inch represents an
actual distance of 3
feet. Method 2 Use the Unit Rate.
1:24 The actual distance is proportional to the map
distance with a ratio of 1 inch
8 miles
1 inch represents an Find the scale factor.
actual distance of 24
units. 1 inch = Convert 8 miles to
8 miles inches.
1 inch
. So the actual
The scale factor is 506, 880 inches
Scale Factor
distance is 506, 880 times the map distance
The amount that an original has been enlarged or (a = 506, 880m).
reduced is called a scale factor.
a = 506,880m Write the equation.

This image has a scale factor 1/3. = 506,880(3.25) Substitute m = 3.25

9 units = 1,647,360 Simplify.
3 units
A 6 units B 2 units The actual distance is 1,647,360
Answer
inches or 26 miles.
1
This image has been reduced by
3
203