31 December 2018
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From New Scientist #1632, 29th September 1988 [link]
Professor E. Mit was somewhat puzzled, as the experiment he had been conducting had been a complete failure. After some investigation the cause was pinpointed to a faulty timing device, which measure time in minutes and hours only, in a 12 hour format with no distinction between am and pm.
Having replaced the offending clock, Mit decided to ascertain the nature of the error. This he did as follows; placing the faulty clock alongside an identical one which was known to keep the correct time and starting both clocks at the same time, he observed that the erroneous clock gained one minute in the first minute, two minutes in the second minute, three minutes in the third minute, and so on. For example, if both clocks start at 12:00:
If both clocks start as above at 12:00 precisely, what time will it be when the faulty clock next shows the correct time?
This puzzle was originally published in the last issue of New Scientist to carry an issue date that falls on a Thursday. Subsequent issues have an issue date that falls on a Saturday.