Aptitude - Clock - Discussion
Discussion Forum : Clock - General Questions (Q.No. 4)
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:
Answer: Option
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.
Discussion:
154 comments Page 1 of 16.
Jaslin said:
2 decades ago
How we got 37/720 ?
Khalid said:
1 decade ago
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:
1 decade ago
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.
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:
1 decade ago
How did you get 185 ?
Swetha said:
1 decade ago
Can anybody tell me how did we get '1/20 hrs of the correct clock' ?
Ajay said:
1 decade ago
@Swetha
3 min converted into hours by dividing with 60.
3/60 hrs = 1/20 hrs.
3 min converted into hours by dividing with 60.
3/60 hrs = 1/20 hrs.
Nitesh Nandwana said:
1 decade ago
@Saranya
(3/60)+(5/(60*60)) = 185/3600 = 37/720.
185, it is simple calculation babes.
(3/60)+(5/(60*60)) = 185/3600 = 37/720.
185, it is simple calculation babes.
Vinu said:
1 decade ago
Any body understand last step? can you explain?
Shyam said:
1 decade ago
why 720/37?
Nitin said:
1 decade ago
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]
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]
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