The scene: fag end of a horribly annoying robotics paper. Have just reached a problem that is in two parts. Part 1, I knew exactly how to do. Part 2, I assumed would never come in a paper, and if it did, 'I'd figure it out.'
So now I'm there, 'figuring it out'. Three possible answers come from the three possible ways of doing the problem - 2.5 years, 3 years and 3.33 years. The numbers are running through my head. After a brief battle in my head, I finally decide on 2.5 years.
About three minutes later, the paper ends. The usual post-paper rapid copying session begins. I wearily close the answer booklet and keep the pen down in disgust.
The guy in front of me looks at another guy,
Guy 1: What's the answer to the payback period problem?
Guy 2: Three years
Guy 1: Great, I got the same answer!
Almost instantaneously, a demon and an angel appear on my shoulders. (Okay, so they don't, but we'll pretend that they did).
Demon: Go on! Change it!
Hands eagerly start looking for the last pages of the answer booklet
Angel: NO WAY!
Sheepish hands keep looking for that page, albeit more slowly
Demon: Come on! You haven't done this for three-and-a-half years. No one will grudge you this once!
Happy hands find the problem
Angel: Now is no time to begin.
Brain starts to think of the method that gives 3 years as the answer
Demon: Al..mo..st.. there!
Brain has decided the changes to be made. Hand slowly moves towards pen
Angel: You decided that 2.5 years made the most sense. YOU made that choice, now see it through, no matter what.
The whole 'back your decisions' thing suddenly snaps the brain out of the angel-demon reverie.
I'm glad I didn't change it. Turned out later that I had 'figured it out' the correct answer. And I'm proud I didn't give in. My sinless record in college survives!