Here I am, as promised, with the answer to the puzzle I posted last year.
Although only one person has been brave enough to claim she’s solved it, a quick glance at my blog statistics tells me that quite a few others dropped in for a look. Either you worked out the solution but were too exhausted by the effort (or just plain lazy) to blow your trumpets; or else – like me – you didn’t, so you couldn’t.
The problem: using two egg-timers that run on sand, one for four minutes and a larger one that goes for seven, how could you time nine minutes…for a ridiculously over-cooked hen’s egg, or perhaps a giant one laid by an ostrich?
It seemed to me that I could only achieve 8 minutes (2 X 4) or eleven minutes (7 + 4.) But I missed something obvious.
Start both the timers off together. When the four-minute one is empty, turn it over immediately to begin another four minutes. The larger timer still has three minutes to go; let it run its allotted time and turn it over immediately to begin another seven. At this point the smaller timer has run three out of its four minutes. Leave it be.
The smaller timer finishes its second run, having totalled eight minutes, still a minute short of the target. But the larger one has only had time to run for one minute so far. Turn it over and its sand will run back for just one minute till it is empty…total elapsed time nine minutes.
Easy peasy. Then why didn’t I see it for myself?
Karen, I assume you worked it out…well done to your Little Grey Cells. You’re obviously in for a very bright and brainy 2012. Let’s hope the rest of us can catch you up.
I wish everyone a very good New Year, with time for happy reading, especially (of course) plenty of puzzling mysteries.