Pre-Algebra Chapter 6 - Ramsey School District

Activity 2
Suppose a store advertises a sale in which all merchandise is 20% off the original
price. If the original price of a pair of shoes is $50, how much will you save?
In this case, you know the percent. You need to find what part of the original
price you’ll save.
You can find the part by using a similar model.
Step 1
Draw a 10-unit by 1-unit
rectangle on grid paper.
Label the units on the right
from 0 to 100 because
percent is a ratio that
compares a number to 100.
Finding a Part
Step 2
On the left side, mark
equal units from 0 to 50,
because 50 represents
the whole quantity.
Step 3
Draw a horizontal line from
20% on the right side to the
left side of the model. The
number on the left side is
the part. Label the model
as shown.
0
10
20
30
40
50
60
70
80
90
100
0
5
10
15
20
25
30
35
40
45
50
0
10
20
30
40
50
60
70
80
90
100
0 0
part 5
10
15
20
25
30
35
40
10 percent
20
30
40
50
60
70
80
whole 45 90 100
50 100
Using the model, you can see that 20% of 50 is 10. So, you will save $10 if you
buy the shoes.
Model
Draw a model and find the part that is represented. If it is not possible to
find an exact answer from the model, estimate.
11. 10% of 50 12. 60% of 20
13. 90% of 40 14. 30% of 10
15. 25% of 20 16. 75% of 40
17. 5% of 200 18. 85% of 500
19. 33 1 % of 12 20. 37.5% of 16
3
Investigating Slope-Intercept Form 287
Algebra Activity Using a Percent Model 287