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 D
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]
The correct time is 9 hrs after 7 a.m. i.e., 4 p.m.