Tick Tock Bad Clock
Math brain teasers require computations to solve.
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?
Answer
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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Comments
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 ... |
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