SOLUTION: The gas mileage, m, of a specific car is a linear function of the speed, s, at which the car is driven,for 60 less that or equal to s less than or equal to 30. if the car is driven

Algebra ->  Functions -> SOLUTION: The gas mileage, m, of a specific car is a linear function of the speed, s, at which the car is driven,for 60 less that or equal to s less than or equal to 30. if the car is driven      Log On


   

Question 296402: The gas mileage, m, of a specific car is a linear function of the speed, s, at which the car is driven,for 60 less that or equal to s less than or equal to 30. if the car is driven at a rate of 30MPH, the cars gas mileage is 35MPG. If the car is driven at 60MPH the cars gas mileage is 20MPG. I need to use this data (s,m) to write an equation for the gas mileage m. I have know idea how to do this!
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
You need to plot this the same way you plot y+=+f%28x%29
Plot gas milage, (m) on the vertical axis and
speed, (s) on the horizontal axis. This is m+=+f%28s%29.
You are told that it's a straight line between s+=+30
and s+=+60.
Essentially what you are given is two points, (s,m) on this line
(30,35) and
(60,20)
Now you need the point-slope formula which looks like:
%28m+-+35%29%2F%28s+-+30%29+=+%2820+-+35%29%2F%2860+-+30%29
%28m+-+35%29%2F%28s+-+30%29+=+-15%2F30
Multiply both sides by s+-+30
m+-+35+=+%28-1%2F2%29%2A%28s+-+30%29
m+-+35+=+%28-1%2F2%29%2As+%2B+15
m+=+%28-1%2F2%29%2As+%2B+50
This is gas milage as a function of speed
Here's a plot:
+graph%28+500%2C+500%2C+-15%2C+110%2C+-15%2C+60%2C+%28-1%2F2%29%2Ax+%2B+50%29+
Remember that the plot is only good between s+=+30 and s+=+60