If I Could Buy Anything- Math is Everywhere

Unit Price and Constant of Proportionality

Explore how unit price and constant of proportionality are related and how they can be represented using a table, a graph, an equation, and a verbal description.[br][br]Think of something that you enjoy and would like to buy the next time you go to the store. For purposes of this activity, keep the price under $10. Use the purple slider to set your unit price.

Use the slider scale to set the unit price. Round to the nearest whole dollar.

Representing a Proportional Relationship Using a Table

Describe the table- do you notice a pattern? How does buying 1 more unit (x) impact the cost?

Finding the Constant of Proportionality from a Table

Divide each cost (y) by the quantity (it's related x). What do you notice?

Everytime I divide the y-value by it's x-value, I get the same answer. There is no pattern. Every answer decreases by 1.

Is there a point on the graph that when extended the line would always cross?

Yes (0,0) - Origin No, there is not.

Representing a Proportional Relationship Using a Graph

Desctibe the shape of the graph.

There is no shape. The graph is a circle. The graph is a line.

Explain the Relationship.

In you own words how you would use the number of items you buy and the unit price to find the cost.

The Origin

What is the cost when the quantity is zero?

The cost is always 1. The cost varies. The cost is 0.

Finding the Unit Price from a Graph of a Proportional Relationship

How can you find the unit price ([i]k=constant of proportionality[/i]) from the graph? Select all that apply.

Just guess. Divide any y value by its related x-value. Find the y-value when x is equal to one.

Using Your Unit Price to Write the Rule. y=kx

Write an equation using your unit price to show the relationship between the quantity and cost.

Use what you know to make a prediction.

What would your total cost be if you were buying 20 items?

What's Your Word Problem?

Write your own word problem using the item you selected and it's unit price.