The number you see over and over again in a proportional relationship
Constant of Proportionality
Elena went to a store where you can scoop your own popcorn and buy as much as you want. She bought
10 ounces of spicy popcorn for $2.50.
1. How much does popcorn cost per ounce?
2. How much popcorn can you buy per dollar?
25 cents
4 ounces
What is the c of p?
2 10
3 15
4 20
5
Is this an equation?
y=kx
Yes
Who is Mr. Currin's favorite student?
Everybody
These letters are on the left and right side of a proportional table
X and Y
At a grocery store, the price of watermelon is determined by how many pounds the watermelon weighs. The price of a watermelon that weighs 7.3 pounds is $4.38.
Create an equation that can be used to determine the price, p, in dollars, of any watermelon based on the number of pounds, w, the watermelon weighs.
p=0.60w
The cost of tickets to a school band concert is shown in the table.

Which equation models the cost of the tickets?
A
c = 5.25t
B
c = 15.75t
C
c = 10.50t
D
c = 26.25t
A. c= 5.25t
Is this an equation?
y=x/1/2
No
How many students are in this class?
25
This is used when simplifying fractions. (i.e. 3/6)
Common Factor
No and there would be no equation
Find the constant of proportionality when it pertains to the formula y/x
X Y
45 9
75 15
60 12
85 17
C of P is 1/5 or 0.2
Is the equation correct?
y=45x
Yes
What is the name of this unit?
Introducing Proportional Relationships
This term is for proportional relationships in regards to y/x
Formula
y=x/9
y=9x
Based on a website, Ellen knows that 5 slices of pizza have 1,900 calories.
If she eats 2 slices of pizza, how many calories does she eat?
760 calories
Mai is filling her fish tank. Water flows into the tank at a constant rate. Complete the table as you answer
the questions.
1. How many gallons of water will be in the fish
tank after 3 minutes? Explain your reasoning.
2. How long will it take to fill the tank with 40
gallons of water? Explain your reasoning.
3. What is the constant of proportionality?
time (minutes) water (gallons)
0.5 0.8
1
3
40
25 minutes
Who has the jwet?
None other than Mr. Currin
This equation is used to solve for constant of proportionality.
y=kx or y=x/k
The cost of tickets to a school dance is shown in the table below.
Number of tickets (t) Cost (c)
2 $14.50
6 $43.50
Which equation models the cost of the tickets? (Think C of P)
c=14.50t
c=7.25t
c=43.50t
c=55t
B. c=7.25t
Based on a website, Ellen knows that 5 slices of pizza have 1,900 calories.
If she only eats 190 calories of pizza, how much pizza does she eat?
1/2
Write an equation for the previous question.
w=1.6t
Where did Mr. Currin move from?
Arkansas