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Math Puzzle: Faulty Clock

 
 
vinsan
 
Reply Mon 10 Jul, 2006 05:58 am
Hi Guys,

A Nice aptitude puzzle for math freaks....

A man installed a brand new clock on a wall in a house and set its time to 12:00 clock noon. He could not notice that the clock has a structural defect that its second, minute and hour arms were located on the central rod with rotatory motor that performs 61 strokes instead of 60 to finish a rotation around itself.

He left the house and came back exactly an year(non-leap) after the incident at the exact same time of 12 in the noon in his handwatch which is absolutely correct. The wall-clock worked for day and night without any further delay.

Q 1. What time must the clock be displaying now ?
Q 2. Assuming that the year is leap, what time must it be displaying now?
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Type: Discussion • Score: 1 • Views: 2,798 • Replies: 17
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fresco
 
  1  
Reply Mon 10 Jul, 2006 08:50 am
Assuming that the rotary arm is geared to a one minute rotation the clock will gain "one second" every minute.

Q1 ordinary year=365x24x60mins
->Clock gains 365x24 mins= 6.08333...days
Time reads 12+2.00=14.00

Q2 leap year=366x24x60 mins
->Clock gains 366x24 mins=6.1 days
Time reads 12+ 2.4 hours =14.24
0 Replies
 
fresco
 
  1  
Reply Mon 10 Jul, 2006 09:01 am
Actually, I'm now thinking it loses a second per minute (one second per stroke)....in which case the two answers are 10.00 and 09.36 respectively. Confused
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vinsan
 
  1  
Reply Mon 10 Jul, 2006 09:55 am
Hint:

The general structure of any clock is that all 3 arms SHARE the central rotating rod.

So the defect (add or loss) is common in all arms i.e. seconds, minute & Hour each as they all lie on the same defective rotatory motor. Only thing is each structs with different momentum being on different sized disks.
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markr
 
  1  
Reply Mon 10 Jul, 2006 10:24 am
I get:
12:23:36.39
and
12:00:00
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vinsan
 
  1  
Reply Tue 11 Jul, 2006 01:53 am
Mark How do you reach a decimal in seconds... ? We normalize the puzzle in the lowest unit of time, that is seconds. So ultimate time must always be in whole seconds.
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markr
 
  1  
Reply Tue 11 Jul, 2006 09:46 am
Because most of the time, N * (60/61) is not a whole number.
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acedogg
 
  1  
Reply Mon 17 Jul, 2006 12:41 pm
this is how I see it..........

For every minute you lose one second
For every hour you lose 60 seconds and one minute
For every day you lose 1440 seconds, 24 minutes and 1 hour

This totals 108 minutes/day
X 365 days=38340 minutes lost for the year

Divided by 60 (for total hours lost for the year)= 639 hours lost in the year

639-624(26 days x 24 hours) (take off all of those whole days, because days don't matter on a standard clock) which leaves you with 15 hours..........

take off those additional 12 which leaves you 3 hours behind so 9 o'clock

my head hurt so I didn't figure out the leap year portion, but I assume it would be pretty easy using the 108 minutes per day loss.
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vinsan
 
  1  
Reply Tue 18 Jul, 2006 07:39 am
acedogg is correct!
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markr
 
  1  
Reply Tue 18 Jul, 2006 08:58 am
I disagree. A second is not lost every minute. A second is lost every 61 seconds.
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tiger12
 
  1  
Reply Tue 18 Jul, 2006 10:03 pm
There are math freaks and then there is markr.

He is correct (as usual).
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acedogg
 
  1  
Reply Thu 27 Jul, 2006 01:54 pm
If the normal clock is at the 60 second mark the faulty clock would still be one second away from being at one minute, hence you lose 1 second every time this happens. If the normal clock is at the 120 second mark the faulty clock would now be 2 seconds away from being at the 120 second mark and so on.
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markr
 
  1  
Reply Thu 27 Jul, 2006 07:58 pm
If the faulty clock takes 61 "ticks" to complete a revolution, then the faulty clock will be at 60 seconds when the normal clock is at 61 seconds. You lose one second every 61 seconds.
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acedogg
 
  1  
Reply Fri 28 Jul, 2006 02:18 pm
markr wrote:
If the faulty clock takes 61 "ticks" to complete a revolution, then the faulty clock will be at 60 seconds when the normal clock is at 61 seconds. You lose one second every 61 seconds.


I agree, but I believe that you would use this reasoning if the question was: "The faulty clock reads 1200 at the end of a year what time did the normal operating clock read?" We are using the given, which is standard time (the wrist watch) so we have to figure out what happens during a given minute and at the end of 60 seconds the faulty clock would be one second (one tick) behind because it takes 61 seconds to get around one revolution. Either way? You explanation is true, I can't argue that, but somehow I did get the correct answer?
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markr
 
  1  
Reply Fri 28 Jul, 2006 08:15 pm
After 60 seconds, you've lost 60/61 of a second. I don't think your answer is correct.
0 Replies
 
thoh13
 
  1  
Reply Fri 28 Jul, 2006 10:11 pm
Quote:
...rotatory motor that performs 61 strokes instead of 60 to finish a rotation around itself


well if each stroke is 60/61 seconds....then wouldn't it not matter and the time would be the same?
0 Replies
 
markr
 
  1  
Reply Sat 29 Jul, 2006 12:04 am
I interpreted the statement to mean that a stroke occurs every second, but it takes 61 strokes to make a complete revolution. After 60 seconds, 60/61 of a revolution has been made.
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acedogg
 
  1  
Reply Tue 1 Aug, 2006 01:07 pm
Okay, I have been thinking about this and this is what I have come up with.........

I asked myself where would the faulty clock be at 60 seconds? The correct answer is it would be at 60 seconds, it is still ticking one click per second like the other clock it just has a longer "complete rotation", so it would be one second short of its own full circle. Now at 120 seconds the faulty clock would be at 120 seconds but it would be 2 seconds away from reaching its goal of two whole rotations because it actually needs to get to 122 to complete two rotations. And so on............Does this make sense or am I obsessing?

At the end of one hour the goal for the normal clock would be 60 seconds x 60 minutes=3600 seconds. and the faulty clocks final goal for the hour would be 61 secondsx60 minutes=3660, but it would still be at 3600, hence losing 60 seconds.
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