LESSON
2.3
Proportional Relationships and
Graphs
How can you use graphs to represent and analyze
proportional relationships?
ADDITIONAL EXAMPLE 2
The graph shows the relationship between the
number of concert tickets purchased and the
total cost for the tickets. Write an equation for
this relationship.
y = 20x
2.3 LESSON QUIZ
7.4.A
The following data was collected on a cheetah. It
ran mile in min, mile in min, and mile
in 1 min.
1. Explain how you know that this is a proportional
relationship.
The ratio of each data set simplifies to 0.75.
2. Identify the constant of proportionality, and write
an equation for the proportional relationship.
0.75; y = 0.75x
The following data was collected on a cheetah. It
ran mile in min, mile in min, and mile
in 1 min.
3. Make a table and a graph of the proportional
relationship.
The following data was collected on a cheetah. It
ran mile in min, mile in min, and mile
in 1 min.
4. Identify a point on the graph that gives the
constant of proportionality as the y-coordinate.
(1, 0.75)
The point (5, 1) is graphed. This represents 1 mile
in 5 minutes, or a unit rate of mile per minute.
The constant of proportionality is and an
equation
for the proportional relationship is y = x.
How can you use graphs to represent and analyze
proportional relationships?
Sample answer:
A graph that is a line through the origin shows a
proportional relationship.