IXL | Find the constant of variation

This graph shows how the cost of Nick's retirement party depends on the number of guests.

100

$10

$20

$30

$40

$50

$60

$70

$80

$90

$100

Cost

Guests

Cost of Nick's retirement party

What is the constant of variation?

$ per guest

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Learn with an example

question

This graph shows how the number of flowers Grace can have in her garden is related to the number of seed packets she purchases.

100

Total number of flowers

Number of seed packets

Flowers in Grace's garden

What is the constant of variation?

Write your answer as a decimal or integer.

flowers per seed packet

key idea

The constant of variation is equal to the slope.

slope

change in y

change in x

solution

Find any two points on the line.

100

Total number of flowers

Number of seed packets

Flowers in Grace's garden

Two points on the line are (0, 0) and (10, 20). Put those points into the slope formula.

slope

change in y

change in x

Plug in (0, 0) and (10, 20)

20 − 0

10 − 0

Plug in (0, 0) and (10, 20)

Subtract

Simplify

The slope is 2. The constant of variation is 2 flowers per seed packet.

Looking for more? Try these:

Lesson: Constant of proportionality

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Teacher tools

Work it out

Not feeling ready yet? These can help:

X.4Find the constant of proportionality from a graph

X.1Find the constant of proportionality from a table

Lesson: Constant of proportionality

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