Did You Find Out? Get the Answer to the Riddle of E-News Issue No. 4, October 2024
Who twisted the clock?
Jens has two different alarm clocks, both of which are powered by electricity. One alarm clock goes two minutes behind every hour, while the other alarm clock goes one minute ahead. One morning when Jens got up, he noticed that both alarm clocks had stopped due to a power failure. The two alarm clocks now show exactly 6.00 am and 7.00 am.
What time did Jens set the alarm clocks correctly the day before?
Solution
The "faster" clock is three minutes ahead of the "slower" clock every hour. In order for the two alarm clocks to achieve a difference of one hour, 20 hours pass (60 : 3 = 20).
After these 20 hours, the "faster" alarm clock is 20 minutes ahead of the actual time (20 * 1 = 20). So at the time of the power cut, it was effectively 6.40 am. If we calculate 20 hours back from this time, we find the time at which Jens set his two alarm clocks, namely at 10.40 a.m. the previous day.
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