leasing of 2 trucks

Question

The Foothill Truck Leasing Company leases 2 sizes of trucks:

 

$30/day plus $0.15/mile or $25/day plus $0.20/mile

'

a) Find the functions describing the daily cost of each truck

b) Sketch the 2 graphs on the same set of axis

c) If a customer plans on driving 70 miles in a day, which truck should he lease?

Answer 1

Alright, Christine.  We have to figure out how to write out a function using what we have.  How much would it cost to drive the first truck 2 miles in one day?  It would be $30.30, right, because we took the $30 and added 15 cents for each of 2 miles.  The second truck would be $25.40 for the same, because you have the daily rate, plus 20 cents for each of 2 miles.

 

Let's let x = the number of miles driven. Then y will be our total.  Then our first equation is y = 30+.15x.  The second is y = 25+.20x.  Make sense so far?

 

If you want to graph, then pick different values for x.  If you drive no miles (x = 0), then what is the y for each truck? Now pick x's like 1, 2, 3, etc, plug them in and find your y's for each.

 

If you make x = 70, then plug in 70 for x and figure out what your y is.