+

# Proportional Webs

##### Rating:
(3)
• (0)
• (2)
• (1)
• (0)
• (0)
Author: Rebecca Newburn
##### Description:

Many relationships are proportional. Learn how to identify them.

(more)

Sophia’s self-paced online courses are a great way to save time and money as you earn credits eligible for transfer to over 2,000 colleges and universities.*

No credit card required

28 Sophia partners guarantee credit transfer.

263 Institutions have accepted or given pre-approval for credit transfer.

* The American Council on Education's College Credit Recommendation Service (ACE Credit®) has evaluated and recommended college credit for 25 of Sophia’s online courses. More than 2,000 colleges and universities consider ACE CREDIT recommendations in determining the applicability to their course and degree programs.

Tutorial

• What is a proportional relationship?
• How can I tell if the relationship is proportional?

## Proportional Relationships

A proportional relationship is when the growth pattern is multiplied by a scale factor.

Situation
We'll be exploring how a relationship can be expressed in a situation. For example, Malia buys bird 1 lb. of bird seed for \$3. If she buys 2 lbs., she would spend \$6. Since she is charged the same amount per pound, and there is no initial fee, this is a proportional relationship.

Table
Malia's Birdseed

 Lbs 1 2 3 4 Cost (\$) 3 6 9 12

You can write each point as a fraction in simplest terms and if they are all equal, then it's a proportion. Ex. because they all simplify to .

Graph
You can tell if a graph is proportional because it is 1) linear (a line) and 2) goes through the origin (0, 0).

Equation
The relationship between the quantities can be written in the form of y = kx. k is the constant of proportionality. The constant of proportionality is the same as the scale factor.

## Proportional or Not Proportional?

For equations, the equation is in the form of y = kx. k is the constant of proportionality. The instructor mentioned that if it is a one-step equation it's proportional. NOTE: y = x + k, which is a one-step equation, is NOT proportional. Only one step equations in the form y = kx are proportional.

Source: Danielle Kunetz

Source: Ms. Newburn