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Puzzle ZDJB 



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At midnight at the start of Monday, January 1st, Professor Stone set two old-fashioned clocks to the correct time.

One clock gains one minute every hour and the other loses two minutes every hour.

When will the clocks next show the same time as each other?
When will the clocks both show the correct time?

Puzzle Copyright © Kevin Stone

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Answer
Midnight after 10 days, which is 240 hours later. They will both show 4 o'clock, one clock will have gained 240 minutes (4 hours) and the other will have lost 480 minutes (8 hours).
Midnight after 30 days, which is 720 hours later. They will both show 12 o'clock, one clock will have gained 720 minutes (12 hours) and the other will have lost 1,440 minutes (24 hours).

 

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