### Brain Teasers

# What's the Correct Time?

I recently gave a new watch to my friend for their birthday. However, as usual with my presents, it was quite useless, as it gains 6 minutes every hour. I set it using my own accurate clock at midnight, and the watch now shows 8:26 am. I know that it stopped 30 minutes ago, so what is the correct time now?

### Answer

8:10 am.Since the watch is gaining 6 minutes every hour, for every real hour that has passed, the watch will show 66 minutes. Since the watch shows 8:26 am, we know that 506 watch minutes have passed. This therefore equals 460 real minutes and hence 7 hrs and 40 minutes. The watch stopped 30 minutes ago, therefore the time must now be 8:10 am.

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## Comments

didn't get it but was cool anyway

That was fun, thanks! good one! It can also be solved by adding the new watch's equivalent of 30 minutes (33) to the NW time and solving for a current NW 'time' of 8:59.

It took a while but it worked out. Good one.

Draw I don't usually like, or even do, the math teasers. This one was fun and you did a very good job explaining to us non math people how to get the right answer - thanks!

Nice and interesting. Got it!

To make the solution a bit clearer for others: the watch is running at 66/60 = 11/10 normal speed, so 10/11 * 506 = 460 minutes passed while the watch was running. Add the 30 minutes and you see that it is 506 - (460 + 30) = 16 minutes earlier than the watch shows.

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