# Worded linear equation problem.

• Oct 13th 2010, 01:11 PM
mathsnub
Worded linear equation problem.
The cost of hiring a car for a day is £50 plus £0.55 per mile travelled. If £y is the cost of hiring a car for a day and x is the number of miles travelled write down the relationship between x and y. Draw the line represented by this equation, identifying the gradient and intercept. If the car is driven 350 in a day, what is the cost of hire? How far can I travel for £150?
• Oct 13th 2010, 01:39 PM
raphw
You are just asked to setup a function. What you need to do is to write down:

y(x) = "fixcost" + "cost per mile" * x. Then you need to solve this for x = 350. For the second question set y = 150 and solve for x.
• Oct 13th 2010, 01:43 PM
mathsnub
I'm totally confused... don't I need to do it in a graph?
• Oct 13th 2010, 01:46 PM
pickslides
Quote:

Originally Posted by mathsnub
I'm totally confused... don't I need to do it in a graph?

you can read the answer from the graph once you have established the relationship or you can substitute in the values.
• Oct 13th 2010, 01:48 PM
mathsnub
This right then?

350*0.55 = £192.50 + £50 = £242.50. Thats the cost for 350 Miles a day.

150-50 = 100. 100/0.55 = 181.81 Miles. Thats the amount of miles for £150.
• Oct 13th 2010, 02:00 PM
pickslides
Quote:

Originally Posted by mathsnub
This right then?

350*0.55 = £192.50 + £50 = £242.50. Thats the cost for 350 Miles a day.

150-50 = 100. 100/0.55 = 181.81 Miles. Thats the amount of miles for £150.

yep.
• Oct 13th 2010, 02:04 PM
mathsnub
Any way I can input all of this into excel to make a graph?

I have no idea on where to start
• Oct 13th 2010, 02:08 PM
raphw
As far as I know you can plot such functions in Excel without giving values. There are many programs however, that do the same job. If you use a Mac e.g. Grapher is installed on your system. For Windows there exists plenty of freeware.

If you want to draw it on paper, however: This function is linear. That means that it will be drawn as a line since the relative change from x to y remains the same over all values of the function. Calculate two random values (what you already did) and draw a line that connects both points. This will be your graph of the function.
• Oct 13th 2010, 02:10 PM
mathsnub

What do I actually input in excel? How do I write it etc as I have no idea lol
• Oct 13th 2010, 02:31 PM
raphw
I dont use Excel myself but if you enter plot function into Google you will find plenty of online tools. What is wrong with just drawing it? All you need for that is a ruler.
• Oct 13th 2010, 02:33 PM
mathsnub
what numbers do I put on the x and y axis? I have no clue on how to draw the graph. Not done Maths in years!

Need help drawing it lol
• Oct 13th 2010, 02:42 PM
raphw
Take the two points you calculated (any other points would do it) and connect them as a line.
• Oct 13th 2010, 02:50 PM
mathsnub
What does the y and x axis go up in?
• Oct 13th 2010, 04:23 PM
raphw
This is pretty basic so I just attached the picture.
• Oct 13th 2010, 04:39 PM
pickslides
Quote:

Originally Posted by mathsnub
What does the y and x axis go up in?

You only need to worry about the increment in x, y will be dependant on that. Attachment 19325