Chapter 5
5.2: Representing Direct Proportion Graphically
Objective…
Part A: Use a Graph to interpret Direct Proportion
•
Each time the wheel on Mike’s unicycle goes around, the unicycle
moves forward 2 meets. The distance the unicycle moves forward is
directly proportional to the number of revolutions.
o The point (1, 2) can be used to find the constant of
proportionality.
o y = kx
Practice…
• Tell whether the graph represents a direct proportion. If so, find the
constant of proportionality. Then write a direct proportion equation.
Chapter 5
5.2: Representing Direct Proportion Graphically
•
Jonathon works at a bookstore. The amount of money he earns is
directly proportional to the number of hours he works. The graph
shows the amount of money, w dollars, he earns in t hours.
o Find the constant of
proportionality. How much
money does Jonathon earn per
hour?
o Write a direct proportion
equation:
_____________________
o Explain what the point (2, 30)
represents in this situation.
Chapter 5
5.2: Representing Direct Proportion Graphically
•
Ms. Gray is driving on a long distance trip. The distance she travels is
directly proportional to the time she travels. The graph shows the
distance she travels, y miles, after t hours.
o Find the constant of proportionality. How much does Jonathon
earn per hour?
o Write a direct proportion equation: _____________________
o Explain what the point (7, 350) represents in this situation.
o Find the distance traveled in 3 hours.
o How long does it take Ms. Gray to travel 400 miles.