On Valentine's Day in 1996, there was a snail (his name is Herb) at the bottom of an empty well that is 30 feet tall. The well had run dry, but it had slippery, moss covered walls. So, during the day (he woke up at 6am), Herb was able to climb 3 feet up, but while he slept at night (he went to sleep at 10pm), he slipped back down 2 feet.

On what date did Herb get out of the well?

(In reply to re: Comments by Tristan)

That one's not exactly orginal either, I remember it from a lateral thinking book I was given as a child (about 20 years ago). But as you say, just cos it's old/non-original doesn't mean it's not interesting or challenging.

I think this snails puzzle is a great one for teaching children to think through to the end of a problem. It's really easy to work out that the snail effectively climbs 1 foot per day, but then many leap to the (incorrect) solution that therefore it must take 30 days to climb 30 feet. And then SK's added the twist of starting on Valentine's day in a leap year to introduce the chance of another error, which is variation on the problem that I've not seen before.

Posted by fwaff on 2003-11-28 03:21:42