Main content

## Algebra (all content)

### Unit 1: Lesson 7

Dependent & independent variables- Dependent & independent variables
- Dependent & independent variables: graphing
- Dependent & independent variables: equation
- Independent versus dependent variables
- Tables from equations with 2 variables
- Match equations to coordinates on a graph
- Relationships between quantities in equations

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# Dependent & independent variables

CCSS.Math:

Identifying the dependent and the independent variables in a word problem. Created by Sal Khan.

## Video transcript

On your math quiz, you earn
5 points for each question that you answer correctly. In the table above, q represents
the number of questions that you answer correctly
on your math quiz, and p represents the
total number of points that you score on your quiz. The relationship between
these two variables can be expressed by the
following equation-- p is equal to 5q, where
p is the points you get and q is the number of questions
you answered correctly. And you could see
that in the table. If q is 0, if you got
no questions right, you get 0 points. If you got no questions
right, well, 5 times 0 is going to be 0. If you get one question
right, well, 1 times 5 is 5. You get 5 points per question. Two questions right,
well, 2 times 5 is 10. 3 times 5 is 15. So this all makes sense. So then they ask us, which
of the following statements are true? Check all that apply. So let's think about this. They say the
dependent variable is the number of points you score. So when you think about
what's happening here, is your number of
points you score is being driven by how many
questions you get right. It's not like somehow the
teacher says you got 15 points and now you have to get
exactly three questions right. It's the other way around. The number of
questions you get right is the independent
variable, and that's driving the number
of points you score. So the number of
points you score is the dependent variable. And typically, the convention is
to have the dependent variable be equal to some
expression involving the independent variable. And you see that
right over here. p is dependent on
what happens to q. Depending on the
number of questions, you multiply it by
5, and you get p. So the dependent variable is
the number of points you score. The dependent
variable is the number of questions you
answer correctly. No, we've already
talked about that. That's the independent variable. The independent variable is
the number of points you score. No, that's not right. That's the dependent variable. The independent
variable is a number of questions you
answer correctly. Well, that's right. That's what's driving
the dependent variable. And we can check our answer.