"I never think of the future. It comes soon enough."
- Albert Einstein
4.
A watch which gains 5 seconds in 3 minutes was set right at 7 a.m. In the afternoon of the same day, when the watch indicated quarter past 4 o'clock, the true time is:
[A].
59
7
min. past 3
12
[B].
4 p.m.
[C].
58
7
min. past 3
11
[D].
2
3
min. past 4
11
Answer: Option A
Explanation:
Time from 7 a.m. to 4.15 p.m. = 9 hrs 15 min. =
37
hrs.
4
3 min. 5 sec. of this clock = 3 min. of the correct clock.
37
hrs of this clock =
1
hrs of the correct clock.
720
20
37
hrs of this clock =
1
x
720
x
37
hrs of the correct clock.
4
20
37
4
= 9 hrs of the correct clock.
The correct time is 9 hrs after 7 a.m. i.e., 4 p.m.
For 9 hrs the clock gains 15 min. Then what about the remaining 15 min in the quarter past 4. ? can't understand. ?
Bala said:
(Fri, Aug 6, 2010 12:19:26 AM)
Hai Jaslin,
To convert mins and secs into hrs we do:
(3/60)+(5/(60*60)) = 185/3600 = 37/720.
I think u might be clear of this.
Saranya said:
(Wed, Sep 29, 2010 04:14:50 AM)
How did you get 185 ?
Swetha said:
(Sun, Oct 3, 2010 04:05:57 AM)
Can anybody tell me how did we get '1/20 hrs of the correct clock' ?
Ajay said:
(Mon, Oct 4, 2010 01:21:22 PM)
@Swetha
3 min converted into hours by dividing with 60.
3/60 hrs = 1/20 hrs.
Nitesh Nandwana said:
(Wed, Oct 13, 2010 05:43:08 AM)
@Saranya
(3/60)+(5/(60*60)) = 185/3600 = 37/720.
185, it is simple calculation babes.
Vinu said:
(Mon, Dec 13, 2010 02:35:48 PM)
Any body understand last step? can you explain?
Shyam said:
(Sun, Dec 26, 2010 12:01:01 AM)
why 720/37?
Nitin said:
(Tue, Dec 28, 2010 08:07:05 AM)
From 7am to 4:15pm the time traveled will be 9 hours and 15 min.
So in minutes it will be (9*60)+15=540+15=555
After every 3 min the clock will add 5 second,so in 555 min no of
seconds that will be added=(555/3)*5=925 seconds=925/60min=15min and 25sec
so the correct time will be=CURRENT TIME(that is 4:15pm)-(15min and 25 sec)
=3:59:35pm
35 seconds in min-->35/60=7/12min
so the correct answer must be 59(7/12) which is ""A""
[But this is wrong, read Sundar's explanation given below]
Smartsuru said:
(Wed, Jan 5, 2011 06:39:10 AM)
A watch which gains 5 seconds in 3 minutes was set right at 7 a.m? what does it actually means?
Ans: Whenever a original clock runs for 3 min (180 sec) the given clock will run 3 min 5 sec (185 sec).
Jimeet said:
(Tue, Jan 11, 2011 09:24:58 AM)
A watch which gains 5 seconds in 3 minutes was set right at 7 a.m?????? what does it actually means??...i had solved it by d way as nitin described..so wts the correct answer,as they hav ignored the 25secs and according to them correct time is 4....wt abt 25 sec....
Archana said:
(Wed, Feb 16, 2011 12:51:41 PM)
Can anyone plz tell me how we got below line?
9 hrs 15 min. = 37/4 hrs.
Sundar said:
(Thu, Feb 17, 2011 12:10:29 AM)
@Archana
It is simple yaar.
9 hrs = (9 x 60) = 540 mins
9 hrs 15 min = (540 + 15) = 555 min.
Now, convert 555 mins to hrs by dividing it by 60 (bcz 60min = 1hr) ok.
Therefore, 555/60 = 37/4 hrs.
That's all. Hope this help you. Have a nice day!
Akhil said:
(Fri, Mar 18, 2011 04:40:12 AM)
NITIN CREATE CONFUSION
Sundar said:
(Tue, Apr 19, 2011 08:49:54 AM)
To: Nitin
You are wrong. The given answer is correct. Don't get confused.
So,
Time passed by Error clock = 9 hrs 15 min.
Time passed by Original clock = 9 hrs.
Therefore, 9 hrs after 7 am is 4 pm.
Note: What was wrong in Nitin's explanation?
555/3 <--- Problem is here.
It should be
555 min/3 min 5 sec [or] 33300/185
Please think twice before solve problem. Hope this will help you. All the best!
Aish said:
(Fri, Apr 29, 2011 06:17:39 AM)
@Sundar:
Nice yaar :-)
Jaya said:
(Sun, Jun 12, 2011 11:16:12 PM)
Thanks sundar. Done in a simple manner.
Faiz said:
(Sun, Aug 7, 2011 10:53:27 PM)
Thanks sundar! :) cheers :).
Gowthami said:
(Sat, Aug 13, 2011 01:43:31 AM)
Thanks ya. This is very simple.
Verkha said:
(Thu, Sep 1, 2011 09:13:48 PM)
How we got 4. 15 pm and 3 min. 5 sec. Of this clock = 3 min. Of the correct clock? Please I'm unable understand.
Anurag said:
(Wed, Sep 21, 2011 08:30:33 PM)
In 3 MIN = The clock gains 5 sec.
in 60 min(3 * 20) = clock gains 100 sec(5 * 20)
= i.e 100/60 min
= 5/3 min
So , If correct clock shows 1 hour=den da wrong clock shows 1 hr 5/3 min..
i.e
1 hr=1 hr 5/3 min
=1 * 5/(3*60) hour (convert to hour)
=37/36 hour
But we need to do reverse..
i.e
37/36 hrs(in wrong clock) = 1 hr
1 hour in wrong clock = 1/(37/36)=36/37 hr
9hr 15min=37/4 hrs
So
37/4 hours in wrong clock =36/37 * 37/4
= 9
So 7 a.m + 9 hrs= 4 pm ....
I hope every1 got it...
Deepak said:
(Tue, Oct 25, 2011 01:14:14 PM)
I have a different view for this question..
Its is straight from the question that the watch gains 1/12 min( 5 seconds) for every 3 min.
Den from 7 am to 4.15 PM its totally 555 min...
Now watch would have totally gained (1/12)*555/3= 15 5/12 min.
Therefore actual time would be (4.15 PM - 15 5/12 min) 3PM 59 7/12 min
Natasha said:
(Wed, Nov 2, 2011 09:12:44 PM)
In 3 min gain is 5 sec
so in 15 min gain is 25 sec
and in 60 min gain will be 100 sec
so in 9 hours and 15 min gain will be
925 sec i.e. 925/60 = 15 5/12
so correct ans is 3pm 59 7/12 min
Tell me whats wrong in my explanation ?
Poornima said:
(Wed, Nov 16, 2011 01:06:26 PM)
The answer in 59 7/12 min past 3.
because 7a.m-4.15p.m toatl time is 9hrs 15mins
Total 555 secs.
actually the clock gains 5secs in 3mins.
then in 555mins the clock gains 15mins5/12sec.
now the clock shows 4.15.
then less the gaining time.
4.15-15mins5/12=59min 7/12secs past 3.
Bhaskar said:
(Thu, Dec 1, 2011 10:35:54 PM)
From 7am to 4:15pm the time gap is 9hr and 15 minutes.
actually there is twenty "3minutes" in an hour.
so for 9hrs 9*20=180(3minutes in 9hrs)
in 15minutes ther are five '3minutes'
So total 185'threeminutes'in between 7am to 4:15pm
So total 185*5=925sec(925\60=15) are fast i.e 15minutes
Meenu said:
(Wed, Dec 28, 2011 01:41:49 PM)
Hi Sundar...
Please help me out.. I did not understand after this step...
[9 hr 15 min = 555 min = 33300 sec]
So,
Time passed by Error clock = 9 hrs 15 min.
Time passed by Original clock = 9 hrs.
Therefore, 9 hrs after 7 am is 4 pm.
Sundar said:
(Wed, Dec 28, 2011 05:41:00 PM)
@Meenu
If Error-Clock passes 185 secs then Original-Clock passes 180 sec only.
So, If Error-Clock passes 33300 secs (ie 9 hr 15 min) then Original-Clock passes 32400 sec only.
Hope you got it. Have a nice day!
C.M.Rafeek.Moothedam said:
(Sun, Feb 12, 2012 10:52:33 PM)
Given->
for 185 seconds of wrong time 180 seconds is correct time;
So 33300 seconds of wrong seconds what will be the correct seconds?
Surely its 180*33300/185 ie 32400 seconds. ie 9 hrs (32400/3600).
To get the correct time add 9 hrs to 7.00 am ie 4.00 pm
****************************************************************
How I got 33300 seconds ?
From 7.00 am to 4.15 pm its 9 hrs and 15 seconds ie 9*60*60 + 15*60 seconds =33300 seconds )
Is it simple ?
Chandana said:
(Fri, Jun 8, 2012 08:43:53 PM)
Can anybody explain clearly how 37/4hrs of wrong clk converted to 9hrs of correct clock.
Puneet said:
(Sat, Jun 9, 2012 05:04:42 PM)
Hey if looking pointwise wats wrong in this :-
3 min = 5 sec
total min. covered uptill 9:15 is : 555 min. =5/3 * 555 == 925 sec (toatl error)
Now converting into min:- 925/60= 15 5/12 min
Subtracting from the time right now to get actually what the error:- 4 hrs 15 min- 15 5/12 min
Ans:- 59 7/12min past 3 hr
Mamta said:
(Tue, Jun 19, 2012 12:20:36 PM)
Hey friends can't we do in this way.
3min=5sec.
1hr=100sec.
9. 15hr=925sec.
925/60=15 min.
So the excess time is 15 min.
So, 9.15 hr-15min = 9hr.
i.e. 4 P.M.
Mohan said:
(Sat, Aug 18, 2012 10:10:03 AM)
@Mamta.
Thanks. Your explanation is good and very easy to understand.
Rinkul Kamboj said:
(Mon, Oct 29, 2012 04:46:52 PM)
We do it in this way.
3min=5sec.
1hr=100sec.
9.15hr=925sec.
You made mistake now in division
925/60=15 min.
But ans will be 925/60=15.416667 or 15 7/12
So the excess time is 15 min.
So, 9.15 hr - 15min7/12sec = 59 7/12min past 3 hr.
P.V.N said:
(Fri, Feb 8, 2013 08:43:33 PM)
For 9 hrs its 9x60=540 minutes.
In 540 minutes (540/3)=180 i.e 180 times 3 minutes are there for each 3 minute it is 5 second then 180x5=900 seconds 900/60=15 minutes, which is extra to be subtracted from 4.15 pm. So 4 is the answer.
Vivek said:
(Mon, Mar 4, 2013 01:24:35 AM)
x+((x*5)/(3*60))=555*60.
Find x?
x is the seconds between 7am and correct time.
555 is minutes between 7am and wrong time.
Find x and convert to hrs getting x as 32400 sec.
Then converted to hrs.
32400/3600= 9 hrs.
7am+ 9hrs=4PM.
Nagesh Einstein said:
(Tue, May 14, 2013 10:23:21 AM)
Actually Sundar's explanation is correct.
Don't get confusion. The question is about two clocks (accurate clock and the error clock). So many of you confused.. 59 7/12 past 3 is wrong because, you are considering only one clock.. you went wrong while dividing 555 minute by 3.. in reality... 555 minutes are passed in ERROR CLOCK,
So you must divide 555 by 3 min 5 seconds (OR 555*60=33300 seconds divided by 3*60+5=185 seconds) Then you will get the right answer.
The correct time is 9 hrs after 7 a.m. i.e., 4 p.m.