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## Pre-algebra

### Course: Pre-algebra>Unit 7

Lesson 8: Dependent and independent variables

# Dependent and independent variables review

Identify dependent and independent variables and apply them to contexts.

## Independent variable

An independent variable is a variable that represents a quantity that is being manipulated in an experiment.
$x$ is often the variable used to represent the independent variable in an equation.

### Example:

You are doing chores to earn your allowance. For each chore you do, you earn $\mathrm{}3$.
What is the independent variable?
The independent variable is the amount of chores you do because this is the variable you have control over.

## Dependent variables

A dependent variable represents a quantity whose value depends on how the independent variable is manipulated.
$y$ is often the variable used to represent the dependent variable in an equation.

### Example:

Let's use the same context.
You are doing chores to earn your allowance. For each chore you do, you earn $\mathrm{}3$.
What is the dependent variable?
The dependent variable is the amount of money you earn because the amount of money you earn depends on how many chores you do.

## Practice

Problem 1
You are buying boxes of cookies at a bakery. Each box of cookies costs $\mathrm{}4$.
Which of the following statements are true?

Want to try more problems like this? Check out this exercise.

## Want to join the conversation?

• What is dependent variable of c=40n+180
• It depends, lets use an example to explain this.

Let's say c is the number of miles you've driven in a vehicle,
And let's say n is the amount of fuel your vehicle uses in milliliters(ml).

So the independent variable is n,
and the dependent variable is c,

since the amount of fuel used depends on the distance you've traveled in miles.

now if u want to do some math's...
the equation given is c=40n+180

so to solve for c we have to input any value for n

example:

n=1, c=(40*1)+180 c=220
n=2, c=(40*2)+180 c=260

to solve for n...
rearrange the equation...
c=40n+180
-180(from both sides)
now... c-180=40n
/40(both sides)
...(c/40)+(180/40)=n

input values for c into the new equation

c=1, n=(1/40)+(180/40) n=0.025+4.5 n=4.525
c=2, n=(2/40)+(180/40) n=0.05+4.5 n=4.55
• why is the question in kilometres but the answers are in miles?
• too much knowledge to fit in my brain
• This is a bit confusing but i will try to understand it
• basically the dependent variable is the number that changes based on what you change the independent variable to, and the independent variable is the number that you are changing on purpose.
(1 vote)
• 5 hours is required but what about the tests we may have not completed?

Please vote and I will vote for you
• Why will dependent and independent variables help me when i'm out of school and college?
What will it do for me?