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Lesson 4: 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 dollar sign, 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 dollar sign, 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
• Current
You are buying boxes of cookies at a bakery. Each box of cookies costs dollar sign, 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?
• I wonder. But it doesn't matter, as long as you understand the principles.😊
(1 vote)
• This is a bit confusing but i will try to understand it
• After finally understanding how this works, here is what I know so far. Let's say we have graph coordinates that say
(0,2)
(2,6)
(3,8)
the relationship between these coordinates is y=2x+2.
Let's take the coordinate (2,6) for example, 6 is the y coordinate and 2 is the x coordinate. The equation y=2x+2 is replaced with the variables 6=2×2+2.

(If a variable and a number are next to each other it means those 2 numbers are being multiplied.)

if anyone is confused, the y variable is being a dependent variable (the one your solving for), then you replace that y variable with the y coordinate. Then you do the same thing with the x coordinate. That's how you solve independent and dependent variables on a graph.
• This is not coordinates
(1 vote)
• I get both of them confused. How do I tell the differences of Dependent and Independent variables?
• is the world a simulation
• It is not.
• too much knowledge to fit in my brain