Things to Learn

  • Identify the same value relating the measures of `x` and the measures of `y` in a proportional relationship as the constant of proportionality and recognize it as the unit rate in the context of a given situation.
  • Find and interpret the constant of proportionality within the contexts of problems.

National Forest Deer Population in Danger?

Vocabulary

A variable is a symbol (such as a letter) that is a placeholder for a number.

If a proportional relationship is described by the set of ordered pairs (x, y) that satisfies the equation y = kx for some number k, then k is called the constant of proportionality. It is the number that describes the multiplicative relationship between measures, x and y, of two types of quantities. The (x, y) pairs represent all the pairs of numbers that make the equation true.

Note: In a given situation, it would be reasonable to assign any variable as a placeholder for the given measures.

For example, a set of ordered pairs (t, d) would be all the points that satisfy the equation d = rt where r is the constant of proportionality. The value for r specifies a number for the given situation.

Mom says, “You needWHAT?”

French Class Cooking

Lesson Summary

If a proportional relationship is described by the set of ordered pairs (x, y) that satisfies the equation y = kx for some number k, then k is called the constant of proportionality.

Exercises and Practice
Click the link to justify more ratios.

Before You Go