SOLUTION: I need to find the mileage when a truck is travelling at 65 miles per hour. I know that the truck is traveling 260 miles and gets 7 miles to the gallon. For each mile per hour incr

Algebra ->  Customizable Word Problem Solvers  -> Travel -> SOLUTION: I need to find the mileage when a truck is travelling at 65 miles per hour. I know that the truck is traveling 260 miles and gets 7 miles to the gallon. For each mile per hour incr      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


   



Question 697857: I need to find the mileage when a truck is travelling at 65 miles per hour. I know that the truck is traveling 260 miles and gets 7 miles to the gallon. For each mile per hour increase in speed, the truck loses a teth of a mile per gallon in its mileage. This is a part of a huge problem, but I just need help on how to solve this part.
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
This looks like a linear relation between milage, +m+
and speed. They give you a point, ( s[1] , 7 )
if you plot milage on the vertical axis and miles driven
on the horizontal axis. They are also giving you the
slope of the line. Slope = +-.1+%2F+1+
But you didn't give me a speed, +s%5B1%5D+ when the milage
is +7+ miles/gallon.
If +s%5B1%5D+ is given, I can set up a point-slope formula:
+%28+m+-+7+%29+%2F+%28+s+-+s%5B1%5D+%29+=+-.1%2F1+
This would give you the equation
+m+-+7+=+%28-1%2F10%29%2A%28+s+-+s%5B1%5D+%29+
+10m+-+7+=+-s+%2B+s%5B1%5D+
+10m+=+-s+%2B+s%5B1%5D+%2B+7+
+m+=+%28-1%2F10%29%2As+%2B+%28+s%5B1%5D+%2B+7+%29+%2F+10+%29+
----------------------------------
Like I said, you need +s%5B1%5D+, the speed at which
the milage is +7+ mi/gal