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Course: Grade 8 (VA SOL)>Unit 4

Lesson 5: Dependent & 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
• 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)
• I get both of them confused. How do I tell the differences of Dependent and Independent variables?
• this is confusing and i need help
and one more thing WHY DID THEY HAVE TO ADD LETTERS?! :(
• I have no idea.
(1 vote)
• Why will dependent and independent variables help me when i'm out of school and college?
What will it do for me?
• Alternatively ,could the no. of boxes I buy depend on the price ?(here price being the independent variable that influences the no of boxes). for ex- say I want to buy 4 boxes of cookies but each box turns out to be 20$,this info then influences me to buy 3 boxes instead of 4 because of high individual cost of each box. (2 votes) • That's only if you have a budget of 20$ :)
• identify the variable being described by following measurement 25m,5m/s,87min,11mi,67 m/s2,8.9s, 3.2km/hr,4.5mi/hr2,2 hr, 5.3km help me plsss! thank youuuu
• What is a dependent and independent variable?
• Are the variables complicated numbers, like do they have to have 2 numbers, or can they have one For example,x=t2 something like that, Can they?
(1 vote)
• Variables are basically the letters in an equation. Their value can vary. For example, let's say that I work x hours a day, and for each hour I work I get \$2.55. Since x is uncertain, it is a variable.