You have two watches:
- Clock A: is completely stopped.
- Clock B: works, but goes back exactly 1 minute every hour.
Which of the two keeps the correct time more times?
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The two broken clocks
Hints
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- First step: A stopped clock matches the real time twice every 24 hours.
- A clock that loses 1 minute per hour loses 12 hours in 720 hours (30 days), so it only matches twice every 30 days.
- Final stretch: A stopped clock matches the real time twice every 24 hours. Then, a clock that loses 1 minute per hour loses 12 hours in 720 hours (30 days), so it only matches twice every 30 days.
Solution
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Answer: The clock stopped.
Explanation:
- A stopped clock matches the real time twice every 24 hours.
- A clock that loses 1 minute per hour loses 12 hours in 720 hours (30 days), so it only matches twice every 30 days.
Therefore, the stopped clock is right much more often.
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