Max and Min (1 Viewer)

[Lukybear]

The cost of operating a truck on a highway is made up of running costs plus the driver's wage. The running costs are (0.25 + s/250) dollars per kilometre where S is the speed of the truck in km/h and the truck dirver's wage is $45 per hour.

At what speed should the driver travel to make a 750 km trip as economical as possible.

 

[Lukybear]

Did any1 get sqrt(11250) as an answer?

 

[addikaye03]

The cost of operating a truck on a highway is made up of running costs plus the driver's wage. The running costs are (0.25 + s/250) dollars per kilometre where S is the speed of the truck in km/h and the truck dirver's wage is $45 per hour.

At what speed should the driver travel to make a 750 km trip as economical as possible.

Total cost =$45t + 750(0.25+s/250) where t=time

Since S=d/t; t=d/s where d=750km so

Total=45(750/s)+750(0.25+s/250)

So just change it to T=33750s^-1+ (375/2+s/250)

Dt/ds= -33750/s^2+1/250 then its just a normal problem from there, test a point before and after minimum t.p etc

you right now?

 

[Lukybear]

Yea i got that. But I think, you missed a line of working. It should be 33750s^-1 + (750(125/2+s/250). I think...