Friday, Noveber 20 Last Friday was Friday 13th. Some facts ... Friday has been regarded as an unlucky day by many over the centuries, the British navy for one. In the UK also Friday was for many years the day of execution of criminals and commonly called "hangman's day". Jesus was crucified on a Friday and the Last Supper seated 13 - which is why many dislike 13 to dinner, at least without a teddy bear. However the number 13 has been related to bad luck long before Christianity; for in Norse mythology there is also a reference to 12 Gods feasting at a table, when Loki (Spirit of Strife) gatecrashes and provokes a quarrel which leads to the death of Baldur, the Gods' favourite. So Friday 13th evokes superstition of disaster. But in fact every year must mathematically have at least one Friday 13th (that is a good puzzle to work out!). When it occurs three times in a year (and it can never be more) it is regarded as predicting a national or global catastrophe (three being also viewed (by some) as unlucky). The last time it happened was in 1987.... And it is also the case this year... OK. Here's the fun part ... There are 2 pieces of string, made of different materials and of different lengths. Each piece of string takes exactly 1 hour to burn from one end to the other end. The speed of burning is not uniform throughout, so it can burn quickly at first and then slowly, or in any random way. If you are given only these 2 pieces of strings and a box of matches, how do you measure 45 minutes? (The solution only requires you to burn the strings. No other action like cutting, measuring, etc. is involved. There is no silly trick.) Apparently this was set by a Professor for a Ph.D qualifying exam at Stanford (subject unknown). You are expected to answer in 15 minutes ... Answer next week! November 13 |October 31 |October 23 |October 16 | October 09
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