I’ve been feeling a bit like the poor Scarecrow today…nothing but straw in my head.
Having had an indolent Christmas, I decided to prepare for the New Year by exercising my Little Grey Cells on a puzzle my husband found this week. And goodness, they certainly need a workout. After two hours trying to do other things while cogitating the conundrum, I couldn’t solve it, till he gave me a couple of clues. And then it seemed so obvious…
So I thought I’d inflict it on everyone else. We’re all going to need our Little Grey Cells in 2012.
Imagine you’ve got two of those old-fashioned egg-timers in which it takes a set time for sand to run from top to bottom of an hourglass-type thingy, (sorry about the technical terminology!) and then you turn the timer over and start again. I always think of them as egg-timers anyhow, and one of these in the puzzle runs for four minutes, but the other runs for seven, which would make for well-cooked eggs.
Anyhow, using these two gizmos alone, the four-minuter and the seven-minuter, how can you time nine minutes exactly? OK, maybe not for an egg…but nine minutes dead, in real time?
I promise you it can be done, and it isn’t a trick question involving, say, looking at your watch while the sand is running, or dashing out to another room to consult a clock on the wall. Nor are you allowed to smash the timers up and re-use the sand in a nine-minute model which you have conveniently to hand. No tricks of any sort: just logic.
If you can work it out, do feel free to boast that you’ve done it… but please don’t spill the solution publicly just yet! I’ll return in 2012 with the answer. If your LGC’s are in the same post-Christmas torpor as mine, when you see the resolution, you’ll kick yourself. I did!
Meanwhile, a very happy and successful New Year to everyone.