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Puzzle ZFEW 



??

I was recently given a new watch for my birthday.

However, as usual with my presents, it was quite useless as it loses 6 minutes every hour.

I set it using my friend's accurate watch at midnight, and it now shows 10:39am.

I know that the watch stopped 21 minutes ago, so what is the correct time now?

Puzzle Copyright © Kevin Stone

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Answer
12:11pm.

Reasoning
The watch now shows 10:39am, so we know that 10 x 60 + 39 = 639 watch minutes have passed.

Since the watch is losing 6 minutes every hour, for every real hour that has passed, the watch will show 54 minutes.

So, 639 ÷ 54 ≈ 11.8333 real hours have passed.

This equals 710 minutes, which is 11 hours and 50 minutes = 11:50am.

The watch stopped 21 minutes ago, therefore the time must now be 12:11pm.

 

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