About this video
A quiz gives 5 points per correct question, so points p and questions q are linked by p = 5q. The video explains that the number of questions you get right is the independent variable, and the points you score depend on it, so points are the dependent variable.
You'll be able to
- use an equation like p = 5q to find one variable from the other.
- decide which variable is independent and which is dependent in a real situation.
- explain why the dependent variable is usually written alone on one side of the equation.
Key words
- variable
- A letter that stands for a quantity that can change, like q for questions right.
- independent variable
- The quantity that drives the change; here, the number of questions you answer correctly.
- dependent variable
- The quantity that changes because of the other one; here, the points you score.
- equation
- A statement that two expressions are equal, such as p = 5q.
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.
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