Enigma 1018: Half-time
22 March 2019
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From New Scientist #2174, 20th February 1999 [link]
Professor Dolittle shades in those squares corresponding to one of his lectures. He has at least one lecture a day (and on some days he actually has more than one) and no two consecutive days have exactly the same lecture times. On just one day he has no afternoon lectures. Dolittle only seems to work half the week: it is possible to cut the timetable into two pieces of equal area, with one straight cut, so that one half is completely free of shading.
Someone was needed to give an extra lecture at one of two times next week: the one later in the week was also at a later time of day. I asked the professor if he was lecturing at those times. I knew that his answer together with all the above information, would enable me to work out his complete timetable.
In fact, he was free for just the first of those two times and he agreed to take an extra lecture at that time. If I told you the day of that extra lecture you would be able to work out his complete timetable.
Please send in a copy of the professor’s timetable (without the extra lecture added).
In the magazine this puzzle seems to have been labelled: “Enigma 1081“.