John goes to work painting white lines o

John goes to work painting white lines on the motorway with a tin of paint and a brush, after the first day he accomplishes 4 mile... later that day his boss congratulates him. The next day John paints 2 mile of white lines... so his boss said, "yeh thats acceptable."On the third day he only does 1/4 of a mile... the boss says, "Whats wrong you did 4 mile the first day?"John replies, "Yeh but the tin keeps getting further away"...