IXL | Find the constant of proportionality from a table

Terrence likes to make lemonade using the lemons from his grandmother's trees.

There is a proportional relationship between the number of pitchers of lemonade Terrence wants to make,

and the number of lemons he needs,

x (pitchers)	y (lemons)
2	8
3	12
4	16
5	20

What is the constant of proportionality? Write your answer as a whole number or decimal.

lemons per pitcher

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Learn with an example

question

A mysterious flying superhero known as Blue Sky protects the good citizens of Oxford. Unknown to these citizens, Blue Sky is actually mild-mannered Trudy, a scientist in a flying suit. Before Trudy can fly in the suit, she needs to charge its battery.

There is a proportional relationship between the number of hours Trudy has charged her flying suit,

and the number of hours she can fly,

x (hours charged)	y (flight hours)
1	1
4	4
7	7
8	8

What is the constant of proportionality? Write your answer as a whole number or decimal.

flight hours per hour charged

key idea

Two variables have a proportional relationship if the ratio of one variable to the other is constant.

If x and y have a proportional relationship, the constant of proportionality is the ratio of y to

solution

To find the constant of proportionality, calculate the ratio of y to

x (hours charged)	y (flight hours)	Ratio of y to x (flight hours per hour charged)
1	1	1 1 = 1
4	4	4 4 = 1
7	7	7 7 = 1
8	8	8 8 = 1

The ratio for each pair of

and

y-values

So, the variables have a proportional relationship.

So, the constant of proportionality is 1 flight hour per hour charged.

Looking for more? Try these:

Lesson: Proportional relationships

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