Graphing: find linear eqn for fee f in x yrs; find ramp grad

[kaymarie]

When it was 2 years old, the annual registration fee for a dodge caravan was $380. When it was 4 years old, the registration fee dropped to $310. If the relationship is linear, write an equation that gives the registration fee f in dollars for the van where it is x years old.

Find the grade of the ramp 24ft at the bottom and 2ft on the side. Round to the nearest tenth of a percent.
The answer is 8.3% i have no idea how they got that

Thanks so much

 

[mmm4444bot]

Re: Graphing word problems



Hi Kay Marie:

Will you please do us a favor and start including in your posts some statements that tell us why you're stuck. If you're able to do any work at all, then we like to see that also.

I have no idea what you know about "slope". If you had given me a clue, then I would have a good idea of what type of help that you need.

We're volunteers here; not everybody has time to type up an entire lesson for posters.

In your first exercise, they tell you that the relationship between vehicle age and registration fee is LINEAR.

If you call age X and you call the fee Y, then this linear relationship has a graph that's a straight line, and an equation (formula) that relates X and Y can be written many ways.

For beginners, the most common forms are Y = M*X + B and Y - Y[sub:c3h4132w]1[/sub:c3h4132w] = M * (X - X[sub:c3h4132w]1[/sub:c3h4132w]).

M is the slope. You calculate it using the Slope Formula with the coordinates of two points on the line. They gave you these coordinates.

On the second exercise, "grade" is the same as slope. Have you heard of slope defined as RISE OVER RUN?

This ratio of rise over run is a fraction. All fractions can be interpreted as a percent. So, calculate the slope using the rise divided by the run, and then multiply the decimal approximation of this fraction by 100 in order to express it with a percent sign.

I realize that I've left out several pointers, but why should I invest my time typing a bunch of stuff that you already know? (And, if you don't know it, then how am I supposed to know THAT?)

If you need further assistance, then please show us any work that you are able to accomplish, and TRY to say something about why you're stuck.

Cheers,

~ Mark

 

[Deleted member 4993]

Re: Graphing word problems

When it was 2 years old, the annual registration fee for a dodge caravan was $380. When it was 4 years old, the registration fee dropped to $310. If the relationship is linear, write an equation that gives the registration fee f in dollars for the van where it is x years old.

you are given two points - you are asked to find the equation of a straight line through those points.
Equation of a straight line through (x[sub:i93go7zd]1[/sub:i93go7zd] , y[sub:i93go7zd]1[/sub:i93go7zd]) and (x[sub:i93go7zd]2[/sub:i93go7zd] , y[sub:i93go7zd]2[/sub:i93go7zd]) is:

[y - y[sub:i93go7zd]2[/sub:i93go7zd]] / [y[sub:i93go7zd]1[/sub:i93go7zd] - y[sub:i93go7zd]2[/sub:i93go7zd]] = [x - x[sub:i93go7zd]2[/sub:i93go7zd]] / [x[sub:i93go7zd]1[/sub:i93go7zd] - x[sub:i93go7zd]2[/sub:i93go7zd]]

Find the grade of the ramp 24ft at the bottom and 2ft on the side. Round to the nearest tenth of a percent. The answer is 8.3% i have no idea how they got that

How does your book/class-notes define "grade"?