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Rate of Change and Initial Value

Rate of Change and Initial Value

Assessment

Presentation

Mathematics

8th Grade

Hard

Created by

James Gonzalez

FREE Resource

8 Slides • 26 Questions

1

Interpreting Rate of Change and Initial Value

Please take notes & concentrate on the questions

2

Bonnie has decided to join a gym for the next 3 months.

Both gyms Bonnie is researching charge a monthly fee but she noticed that there might be other fees she has to pay.

How can she compare the two options to determine the better overall value?​

3

​Bonnie continues to research gym options and finds out that Fabulous Fitness has no sign-up fee, while Greg’s Gym charges $50 for the initial sign-up.

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Take a minute to examine the information before answering the next few questions.

​She makes the following table to help her compare the two options.

4

Fill in the Blanks

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Type answer...

5

Fill in the Blanks

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Type answer...

6

The initial value of any function represents the value of the function at the beginning.

Initial Value

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Fabulous Fitness has an initial value of 0 because they do not charge a sign-up fee.

Greg's Gym has an initial value of 50 because they charge a sign- up fee of $50.

7

Fill in the Blanks

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8

Fill in the Blanks

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9

The rate of change of any function represents the constant value at which the function increases or decreases.

Rate of Change

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Fabulous has a rate of change of 45 because they charge $45 per month

Greg's Gym has a a rate of change of 33 because when split evenly between 3 months, it costs $33 per month.

10

Multiple Choice

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If the data for each gym was graphed on a coordinate plane, which gym would have a point on the origin (0,0)?

1

Fabulous Fitness

2

Greg's Gym

11

The owner of Fabulous Fitness wants to buy name tags for her staff.

She writes the following function to represent the cost, y, for a certain number of name tags, x.

y = $2.00x + $7.00

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12

Multiple Choice

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What is the rate of change (CROC) for the cost of each tag based on the equation?

y = $2.00x + $7.00

1

$2.00 per tag

2

$7.00 per tag

13

Multiple Choice

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What do you think is the initial (starting) value for the cost of the name tags based on the equation?

y = $2.00x + $7.00

1

$2.00

2

$7.00

14

Multiple Choice

What is the rate of change in the equation?
y=8x+6
1
8
2
6

15

Multiple Choice

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Find the rate of change
1
1
2
2
3
11
4
Not a constant slope/Non-Linear

16

Multiple Choice

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Find the rate of change.
1
-2 minutes per gallon
2
-20 minutes per gallon
3
-2 gallons per minute
4
-20 gallons per minute

17

Multiple Choice

Tim bought a new phone.  He paid $125 on the day of purchase, then $50 per month until it was paid off. What is the initial value in this situation?
1
50
2
125

18

Multiple Choice

Tim bought a new phone.  He paid $125 on the day of purchase, then $50 per month until it was paid off. What is the rate of change in this situation?
1
50
2
125

19

Multiple Choice

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What is the initial value of this graph?

1

20000 kg

2

1 h

3

0 kg

4

0 h

20

Multiple Choice

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Analyze the point (3, 27). What does the point represent? 
1
The point (3,27) represents 27 shirts for $3. 
2
The point (3,27) represents $27 for 3 shirts. 

21

Multiple Choice

Which of the following are ways to find the rate of change?
1
change in y over change in x
2
rise over run
3
subtract y coordinates over subtract x coordinates
4
all of the above

22

Multiple Choice

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Which statement describes the rate of change of the line?

1

$20 each week

2

$30 each week

3

$25 each week

4

$70 each week

23

Multiple Choice

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What is the meaning of the rate of change?

1

The cost for the service without any hours of calling is $5

2

The cost of the service without any hours of calling is $6

3

The cost per minute is $0.05

4

The cost per minute is $0.50

24

Multiple Choice

Question image

What is the meaning of the initial value?

1

The cost for the service without any hours of calling is $5

2

The cost of the service without any hours of calling is $6

3

The cost per minute is $0.05

4

The cost per minute is $0.50

25

Multiple Choice

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What is the meaning of the rate of change?

1

Colby's initial deposit was $100.

2

Colby's initial deposit was $150

3

Colby is adding $5 per year

4

Colby is adding $10 per year

26

Multiple Choice

The amount Mike gets paid weekly can be represented by the equation p(α)=2.75a + 200, where a is the number of fashion accessories he sells that week.


Which of the following statements is true?


I. 2.75 is the amount he gets paid per cellphone accessory

II. a is the number of accessories he sells that week

III. p(a) is the total amount he gets paid

IV. 200 is the amount he is guaranteed to be paid each week

1

Statement I only

2

Statements I and II

3

Statements I, II, and IV only

4

All statements I, II, III and IV, are true

27

Multiple Choice

An employer uses the equation

y = 9x + 100 to determine how much to pay his employees for the holidays including a bonus. In the equation, y is the total money paid and x is the number of hours worked. What is the meaning of the initial value?

1

the amount of hours need to earn overtime

2

money earned each hour

3

the bonus for employees

4

the pay for a really good work

28

​Cost of Name Tags

The graph shows how the cost of the name tags for the equation

y = 2.00x + 7.00


x represents the number of tags purchased

y represents the total cost

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29

Fill in the Blanks

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30

As a reminder, when an equation is written slope-intercept form, the "m" represents the slope/CROC

Now we know that the "b" represents the y-intercept or the "initial value" of the function.

Slope-Intercept Form

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OR

INITIAL VALUE!

OR

rate of change!

31

Multiple Choice

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The graph represents the money in a savings account.  

What is the y-intercept and what does it represent in this graph?

1

The initial deposit was $30

2

$30 is added to the account each week

3

It took 30 weeks to same enough money to open an account

4

not enough information

32

Multiple Choice

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The graph represents the height of a burning candle.  

What is the y-intercept of the graph and what does it represent?

1

the time it takes to burn the entire candle

2

the rate at which the candle is losing height

3

the change in the height of the candle each hour

4

the original height of the candle

33

Multiple Choice

An air conditioning salesman earns a base salary plus a commission for each air conditioner he sells.

The equation y = 125x + 375 represents his pay based on the number of air conditioners he sells each week.

What is the slope and what does it represent?

1

The slope is 375 and represents the amount he earns for each air conditioner.

2

The slope is 125 and represents the amount he earns for each air conditioner he sells.

3

The slope is 375 and represents the base salary.

4

The slope is 125 and represents the base salary.

34

Multiple Select

Janice is saving money for retirement. The equation y = 500x + 12,000 models her retirement savings where y is the total she has saved in dollars, and x is the number of months.

Which two statements are correct based on the given equation?

1

Janice started with $500 in her account

2

Janice started with $12,000 in her account

3

Each month, Janice saves an additional $500

4

Each month, Janice saves an additional $12,000

Interpreting Rate of Change and Initial Value

Please take notes & concentrate on the questions

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