The document provides examples of calculating percent change from original to new values, showing a 40% decrease when price drops from $100 to $60, and 119% increase when gas price rises from $1.30 to $2.85. It explains that percent change represents the amount of change relative to the original or starting value.

1. Percent Change
I can calculate the percent change using start and
end data points
Vocabulary:
Percent of change
Percent increase
Percent decrease

2. Percent decrease
Original price = $100
New price = $60
How much did it change?
From 100 to 60 = -40
What percent is this from the start?

3. What percent is -40 from the start
amount (100)?

4. What percent is -40 from the start
amount (100)?
from 100

5. What percent is -40 from the start
amount (100)?
from 100
to 60

6. What percent is -40 from the start
amount (100)?
from 100
to 60 -40

7. What percent is -40 from the start
amount (100)?
from 100
to 60 -40
-40 is what % of 100

8. What percent is -40 from the start
amount (100)?
from 100
to 60 -40
-40 is what % of 100
Change -40 = -0.40... = 40% decrease
Start = 100

9. Write
Define what percent change is.
Explain why 40% decrease is the
percent change in the problem
Be Prepared to explain in class.

10. Percent increase
Price of gas in 1981 was 1.30
Price of gas in 2007 was 2.85
How much did it change?
From 1.30 to 2.85=
What percent is this from the start?

11. Percent increase
Price of gas in 1981 was 1.30
Price of gas in 2007 was 2.85
How much did it change? 2.85
-1.30
From 1.30 to 2.85= 1.55 1.55
What percent is this from the start?

12. What percent is 1.55 from the start
amount (1.30)?

13. What percent is 1.55 from the start
amount (1.30)?
from 1.30

14. What percent is 1.55 from the start
amount (1.30)?
from 1.30
to 2.85

15. What percent is 1.55 from the start
amount (1.30)?
from 1.30 1.55
to 2.85

16. What percent is 1.55 from the start
amount (1.30)?
from 1.30 1.55
to 2.85
100% of 1.30 would be 1.30
1.55 is what % of 1.30

17. What percent is 1.55 from the start
amount (1.30)?
from 1.30 1.55
to 2.85
100% of 1.30 would be 1.30
1.55 is what % of 1.30
Change 1.55 = 1.192... = 119% increase
Start = 1.30

18. What percent is 1.55 from the start
amount (1.30)?

19. What percent is 1.55 from the start
amount (1.30)?
from 1.30

20. What percent is 1.55 from the start
amount (1.30)?
from 1.30
to 2.85

21. What percent is 1.55 from the start
amount (1.30)?
from 1.30 1.55
to 2.85

22. What percent is 1.55 from the start
amount (1.30)?
from 1.30 1.55
to 2.85
100% of 1.30 would be 1.30
1.55 is what % of 1.30

23. What percent is 1.55 from the start
amount (1.30)?
from 1.30 1.55
to 2.85
100% of 1.30 would be 1.30
1.55 is what % of 1.30
Change 1.55 = 1.192... = 119% increase
Start = 1.30

24. Write
Define what percent change is.
Explain why 119% increase is the
percent change in the problem
Be Prepared to explain in class.

25. Percent increase
Member cost last year= $125
Member cost this year= $150
How much did it change?
From 125 to 150 = 25
What percent is this from the start?

26. Percent increase
Member cost last year= $125
Member cost this year= $150
How much did it change?
From 125 to 150 =
What percent is this from the start?

27. What percent is 25 from the start
amount (125)?

28. What percent is 25 from the start
amount (125)?
from 125

29. What percent is 25 from the start
amount (125)?
from 125
to 150

30. What percent is 25 from the start
amount (125)?
from 125 25
to 150

31. What percent is 25 from the start
amount (125)?
from 125 25
to 150
100% of 125 would be 125
25 is what % of 125

32. What percent is 25 from the start
amount (125)?
from 125 25
to 150
100% of 125 would be 125
25 is what % of 125
Change 25 = 0.20... = 20% increase
Start = 125

33. Practice with
whiteboards
7-6 # 1-5

34. Write for your
Portfolio
How do you calculate percent change?
What is the difference bet ween percent
increase and percent decrease?
What does percent change tell you?