1. Scale Drawings & Scale Factor by Luther Allen, M.Ed

2. Ratio Scale A ratio is a comparison of two quantities
A scale is a ratio between two sets of measurements.
Examples:
Drawings: ¼ inch = 1 foot
Maps: 1 inch = 250 miles

3. Scale Drawing (Model)
A scale drawing (model) is a drawing that uses a scale to make an object smaller than (reduction) or larger than (enlargement) the real object.

4. Scale Factor
A scale factor is a ratio used to enlarge or reduce similar figures.
Examples: enlarging a piece of candy for a drawing…or the Willy Wonka Factory…

5. The lengths and widths of objects of a scale drawing or model are proportional to the lengths and widths of the actual object.

6. Practice Problems

7. A set of landscape plans shows a flower bed that is 6. 5 inches wide
A set of landscape plans shows a flower bed that is 6.5 inches wide. The scale on the plans is 1 inch = 4 feet.
What is the width of the actual flower bed?
What is the scale factor?
26 feet
1/48

8. What is the scale factor?
The central chamber of the Lincoln memorial, which features a marble statue of Abraham Lincoln, has a height of 60 feet. Suppose a scale model of the chamber has a height of 4 inches. What is the scale of the model?
Write a ratio of the height of the model to the actual height of the statue?
What is the scale factor?
60ft
4in
15ft
1in
1 inch = 15 feet
1/180

9. Antonio is designing a room that is 20 feet long and 12 feet wide
Antonio is designing a room that is 20 feet long and 12 feet wide. Make a scale drawing of the room. Use the scale 0.25 inches = 4 feet.
STEP 1: Find the room’s length on the drawing (let x = length)
STEP 2: Find the room’s width on the drawing (let w = width) 20 x 4
.25
Length = 1.25 inches = 12 x 4
.25
Width = .75 inches =