An invasion of the North american west coast has left the west without fuel to supply the military vechicles out there. The invaders came from the sea and they consumed all forms of fossil fules until there was none left. They can only be destryed if the tanks and armored vehicles of the defenders can get fuel from the east.

You have a truck that can transport 3000 gallon at a time, but which uses one gallon of fuel for every mile it drives. It is a 3000 mile drivve from east to the west. How many gallons of fuel can you provide if youhave 48000 gallons in your depot?

To transport 48000 gallons in 3000 gallon trucks takes 16 trucks, so uses 16 gallons of fuel per mile it is transported. As soon as the quantity of fuel being transported drops to 45000 gallons (after 187.5 miles), it can be transported in 15 trucks, so uses only 15 gallons per mile. After 200 more miles, 3000 more gallons have been used, so only 14 trucks are needed.

This pattern continues until 18000 gallons of fuel have been transported about 2792.19 miles. The remaining 207.81 miles of transport requires 6 gallons of fuel per mile, so will use 1246.86 gallons. The amount remaining after 3000 miles of transport is about 16,753 gallons.

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This is about 34.9% of the original amount of fuel, very nearly the best possible transport efficiency over this distance.