As a leaving present from his colleagues at work, Simon is given an electric analogue wall clock. On the 1st of May, he sets it up at home moving the hands to the correct time, 8.30h in the morning. However, as it was bought on a very small budget, the timepiece is not that accurate: gaining ten minutes every 24 hours. But while he viewed it at 8.30 every morning, Simon never reset the clock to the correct time. At 8.30 one morning it showed the time as 2.30h. What was the earliest date on which the clock could have shown this time?
Answer: Quite straightforward this week, though the question did garner different interpretations (see below). But the correct answer was 6 June, as provided in order of reply by: John Bowen, consultant, Bromsgrove, UK: Andrew Knox, Rubbond International, Ohé en Laak, The Netherlands; Paul Knutson, textile engineer, Timken Belts, Springfield, Missouri, USA; David Mann, key account manager, SPC Rubber Compounding, UK; France Veillette, chef environnement, Usine de Joliette, Bridgestone Canada Inc., Canada: Stephan Paischer, head of product management special products, Semperit AG Holding, Vienna, Austria. Yanwen Zhou, Conti, China. Congratulations to all above and everyone else who had a go.
As John Bowen neatly explained:
2.30 is 6 hours ahead, so with a gain of 10 minutes or 1/6th hour/day this will be 36 days on, which will be 6th June.
A different interpretation by Jose Padron and Michele Girardi put the clock 18 hours ahead, making the answer 17th August.