If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

Algebra (all content)

Course: Algebra (all content)>Unit 3

Lesson 11: Interpreting linear functions and equations

Linear equations word problem: marbles

Sal finds the y-intercept and the slope of a linear relationship representing someone filling a glass tank with marbles. He then interprets what the y-intercept and the slope mean in that context.

Want to join the conversation?

• Why is this problem in the practice? Shouldn't khanacademy keep their practice problems separate from the problems Sal does in the videos? It doesn't help anyone learn to put in the answer to a problem that they've seen done in a video.
• It helps me because I get to walk through the steps with Sal instead of us doing different problems. It helps me understand the skill better. I then take those steps that I did with Sal and apply them to another problem to help me learn how to do any problem within a certain concept.
• how would you figure this out if you took out the 'n' ?
• What is a function? What does the term, "as a function of" mean?
• A function is a relationship between an input and an output where each unique input value relates to only one output value.

"as a function of x" means that the function is defined for the input value "x".

Hope this helps.
• From to , I didn't understand what the purpose of the function was in this problem. I thought that a function was something that describes a relationship between the input and the output, but this video didn't really make it clear what our input and output was. Was zero supposed to be our function? If so, why didn't we multiply the variable "W" by zero also, and not just on one side of the equation? I understood most of what he said other than this, so help would be appreciated!
• W(n) is equal to W - 0.05(n). However, W(n) seems like W times n, not W minus a product of n. Could someone explain the meaning of W(n), and how it relates to the other side of the equation?
• Did you mean W(n)=32-0.05n? W(n) is read “W of n” not W times n. W(n) is really just y except it is in function notation where n is the independent variable or domain. This follows the same concept as other commonly used function notations: f(x), g(x), h(x), etc (if you’ve seen them before). All those are just another thing for y. I hope that helps :)
• ok so it equels 0.05 ! so confusing :/
• When would we ever use this?
• How does this help us with figuring out other word problems, this video only addresses this one.
(1 vote)
• The concepts taught in this video apply to other word problems. In this situation, you were given the equation. The words describe the equation / function.
1) You should read the problem as many times as needed to makes sure you understand what the function creates and what its input value represents.
2) You should also notice that the equation is in slope-intercept form. So, you can identify the slope and the y-intercept. You should take some time to think thru what that information means in the context of the problem.
3) The questions are tied to asking you for the slope and the y-intercept, but they are done by using info specific to the problem rather than asking you for that info explicitly.

Hope this helps.