What is the ordered pair for the origin?
(0,0)
Is the equation y = 3x proportional? Explain.
Yes. The equation is in the form of y = kx, where k = 3.
Are the ratios below proportional? Explain.
3/4 and 9/12
Yes. If you multiply 3/4 by 3/3 you get 9/12.
The triangles below are similar. What is the value of x?

x = 5
According to the scale on a map, 4 cm on the map equals 32 miles. How many centimeters on the map would represent 384 miles?
48 cm
How do you tell if a graph represents a proportional relationship?
The graph is a straight line that passes through the origin.
Is the equation y = 4x + 10 proportional? Explain.
No. The equation is NOT in the form of y = kx.
Does the graph below represent a proportional relationship? Explain.
No. Although the graph is a straight line, it does not pass through the origin.
Find the value of n in the proportion above.
n = 3.8
Bob ran 66 miles in 12 hours. How many miles did Bob run per hour?
5.5 miles per hour
Does every straight line graph represent a proportional relationship? Explain.
No. The graph would have to be a straight line AND pass through the origin.
What is the constant of proportionality in the equation below?
y= ¾ x
k = ¾
Does the table below represent a proportional relationship? Explain.
No. There is no constant
The table below is proportional. Find the constant of proportionality.

k = 13
The scale for a model airplane to a real airplane is 1in:9ft. Find the wingspan of the model airplane if a real airplane has a wingspan if 171 ft.
19 inches
Find the constant rate of change for this situation.

$2 per DVD
What is the constant rate of change?

$5 per hour
The equation for the linear relationship is y =3x - 8. What is the constant rate of change?
3
How do you show your work differently for proving proportionality vs. constant rate of change?
Proportionality: y / x
CROC: change in y / change in x
Find the slope of the line below:

1
Does this graph represent a proportional relationship? Explain.

Yes. It is a straight line that passes through the origin.
The constant of proportionality for the graph below is 1/6. What is the equation? 
y = 1/6x
Does the table below represent a proportional relationship? Explain.
Yes. The constant of proportionality is 9.
The constant of proportionality is 3. Write an equation for the proportional relationship.
y = 3x
Steve’s car used 38 gallons of gasoline to go 912 miles. At that rate, how many gallons would be used to go 2736 miles?
114 gallons
Find the slope of the linear relationship.
m=2
Write an equation for the proportional relationship shown in the table below.

y = 3/2 x OR y = 1.5x
What is the slope of the line that goes through points (12,9) and (5,2)?
m=(9-2)/(12-5)=7/7=1
The triangles below are similar. What is the value of x?

x = 3
X varies directly with y. If x=12 and y= 15, what would y be x=21?
y=26.25