# How to determine cost function (I really need help on this !)

1. Dec 5, 2004

### ziddy83

Ok here is the problem...
A truck burns fuel at the rate of G(x) gallons per mile, while traveling x miles per hour....Where ..

$$G(x) = \frac {1} {32} \left(\frac {64}{x} + \frac {x}{50} \right)$$

a. Find the cost function C(x) if the truck takes a 400 mile trip. Assume that the cost of fuel is \$1.60 per gallon.

b. What is the speed that will produce minimum cost on this trip?

Ok so....I know how to do this, i was told to find the cost function and then plug in 400 for the x value to find part (a) of the problem. Now for part (b), thats straight forward as well, but...what i need help with is to find C(x) so i can plug those values in. Do i find G' to get C(x)? please...please please!! help me. I have been trying to get help on this for 2 days now and no one has responded to my questions...its pretty frustrating....

2. Dec 5, 2004

### ziddy83

NEvermind...i figured it out myself...