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Math brain teasers require computations to solve.

 Puzzle ID: #49380 Fun: (2.75) Difficulty: (2.02) Category: Math Submitted By: firefox99 Corrected By: FatHead

Your friend gave you a clock for your birthday, but unfortunately, it's very unreliable. This one gains exactly 12 minutes every hour.

It is now showing 10pm and you know that it was correct at midnight, when you set it.

If the clock stopped four hours ago, what is the correct time now?

Since the clock gains 12 minutes every hour, for every real hour that has passed 72 minutes will pass on the clock. It has been 22 fake hours from midnight to the time the clock stopped, so in order to find the number of real hours we must first find the number of fake minutes, then divide the number of fake minutes by the number of minutes that pass by in an hour for the clock (72) to find the number of real hours that have passed from midnight to when the clock stopped. The following shows arithmetic work:

22 x 60 = 1320 (clock minutes that have passed from midnight to when the clock stopped)
1320 / 72 = 18.333333... (real hours that have passed from midnight to when the clock stopped)
18.333333... hours = 18 hours 20 minutes. Therefore it was 6:20pm when the clock stopped. And because the clock stopped four hours ago, it is now 10:20pm!

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 Babe Apr 25, 2012 No comments eh? No wonder, people do not want to go back to school! This is supposed to be a fun quiz, not school work. Enough already!!! thedavincigame Apr 25, 2012 For those looking for a non-mathematical number riddle instead of a complex one: What number's cone alone flour - call ?? HABS2933 Apr 25, 2012 While I don't care for the math based teasers, I know that there are a lot of people who do (otherwise they would not have it as a category). Many people like the "school work" teasers as there are also literature and science type teasers as well. IT was however refreshing to see a brand new teaser (less than a month old) as teaser of the day, much more enjoyable than seeing a teaser that is 5+ years old, the author of which has not even been on the site for almost as long. elentir Apr 25, 2012 I like these teasers! Although, I think this qualifies more as a Math category than Logic. elentir Apr 25, 2012 @thedavincigame - four elentir Apr 25, 2012 I meant one one four - or 114 bradon182001 Apr 25, 2012 Math, definitely not my favorite but this was fun to work out. Good job. charlottes-odd Apr 25, 2012 This reminded me of being back in school haha good puzzle though me likes however... the clock in the riddle lies tripleteam5 Apr 25, 2012 seems wrong. If clock SAYS 10pm that is when it stopped and you add time lost to that It would seem luluw5 Apr 25, 2012 I hate the math teasers! i don't wanna b learnin math!!! dimaspace Jun 30, 2012 Wrong answer! 22 fake hours give us 12"22 equals 264 fake minutes - 4 hours and 24 min So it was 22-4.24 equals 17.36 And plus 4 hours - 21.36 for now or 9.36 pm NOT 10.20 pm Author multiplies 22 by 60 - wrong, he should multiply it by 72 SRB_1807 Jul 20, 2012 the answer is 9:36 p.m ... Author's answer is wrong ... Chura Jul 08, 2013 dont really understand th equestion spikethru4 Jul 09, 2013 dimaspace, the 22 fake hours already includes all the fake minutes. After one hour has passed from midnight, the clock shows 1:12. If F is the fake time in hours and R the real time in hours, then F = R * (1 + 12/60). When the clock stopped, the fake time was 220, so at that point, R = 22 / 1.2 = 18.33, or 6:20pm. Four hours later, the real time is 10:20pm, as stated. spikethru4 Jul 09, 2013 Poxy emoticons. That should be 22 : 00 above.