Here's a lil brain tester.
An automatic light switches on at 18:00, remains on for a whole number of minutes, then switches off and remains off for three times as long as it was on. Then it switches on again, repeats the cycle with the same periods as before and continues. It is seen to be off five seconds before 18:11, to be on five seconds after 21:03 and on again at 22:15. Was it on or off at 22:18? Give your reasons.
An automatic light switches on at 18:00, remains on for a whole number of minutes, then switches off and remains off for three times as long as it was on. Then it switches on again, repeats the cycle with the same periods as before and continues. It is seen to be off five seconds before 18:11, to be on five seconds after 21:03 and on again at 22:15. Was it on or off at 22:18? Give your reasons.