Cat Driver,
I really was hoping that you would ask that question ... although the answer involves some higher mathematics ...and would bore the pants off most of our colleagues ..
Reminds me of two questions posed in my undergrad years in similar vein but which took a lengthy solution to get a tick ...
(a) my fluid mech lecturer posed the following tutorial question along the lines of .. a wartime submarine is disabled on the bottom (lots of data about the sub and depths etc ..) .. how do we get the guys out and to the surface without any third party assistance. The typical answer rambled on via several reams of paper, numerous sums and suchlike ... and, at the end, I penned an impertinent comment to the effect that they would be dead during the ascent anyway due to the depth and other factors ... it was a little embarassing when I got the marked paper back and found his comment "I'm not".
(b) the same guy, in the final exam posed this question. (Background, the old PNR building at SU had a lovely old spiral staircase going up however many floors) .... should the tea lady, having made the tea on the ground floor and put in the sugar ... stir it ... or just walk up the stairs to the top floor .... that answer went on and on also ....
However ... I reminisce and digress ... as usual ..