Puzzle

Q: One of the two army posts, 300 km apart ran out of diesel. The one with ample stock of diesel has a vehicle which can carry 300 lit of diesel, but consumes at a high 1 lit / km of the fuel itself. the entire stretch between the two stations does not have any fuelling station, but at every 50 km there is a fuel storage and transfer bunker, but without any stock at the moment. How much maximum quantity of diesel do you think could be transferred from the post with stock to the other ?'

Ans: The answer is the maximum quantity of diesel that can be transferred is 100 litre. The vehicle starts with 300 lit, drives a distance of 100km, unloads 100 lit of diesel at the intermediate bunker and then returns to the base. It has thus consumed all 300 lit of fuel (200 lit for 200 km driving to and fro and 100 lit storage). Next it takes the balance 300 lit of diesel at the first post, drives upto 100 km point where it had stored 100 lit in previous trip, replenishes the 100 lit diesel it consumed ( during this 100 km drive ) by transferring the 100 lit diesel it stored and drives onwards to the other post. It has still 100 lit of diesel to spare.