1. 3) What is a Scale Drawing/Model?
Warm Up
1) 80 girls and boys are planning to go to a Movie. There is a ratio of 6 girls to 2 boys. How many girls are there?
2) A Chemistry book is comprised of two sections, Organic and non organic in the ratio 2:8. How much of each type of content will be needed to make a book of 400 pages?
3) What is a Scale Drawing/Model?

2. What is a Scale Drawing/Model?
Warm Up
80 girls and boys are planned for a Movie. There are in a ratio of 6 girls to 2 boy. How many girls are there?
80 x 6/8 = 60
Chemistry book comprises of two section Organic and non organic in the ratio 2:8. How much of each type of content will be needed to make a book of 400 pages?
Organic x 2/10 = 80
Non Organic x 8/10 = 320
What is a Scale Drawing/Model?

3. Scale Factor

4. What is the Scale Factor?15 5 B A 3 9

5. What is the Scale Factor?15 5 B A 3 9
◾The scale factor of figure A to B is: (3 * 3 = 9; 5 * 3 = 15)
◾The scale factor of figure B to A is: 1/3 (9 * 1/3 = 3; 15 * 1/3 = 5)
How does the scale factor going from the large figure to the small figure compare to the scale factor of the small figure to the large figure?

6. Practice
Find the scale factor from the LARGE figure to the SMALL figure. 4 1 1 4

7. Find the scale factor from the LARGE figure to the SMALL figure.3 3 18 18 3 18

8. Find the scale factor from the LARGE figure to the SMALL figure.6 9 2 3

9. Find the scale factor from small to large and from large to small for each figure below. Assume figure is similar. 1. 2. 6 24

10. Enlargement
From SMALL to LARGE
Scale Factor > 1
Shrink
From LARGE to SMALL
Scale Factor < 1

11. Percent of Change
The percent of change is the ratio of the amount of change to the original amount.
When an amount increases, the percent of change increases.
When the amount decreases, the percent of change is negative (percent of decrease).
Percent of change = amount of change
original measurement