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:
157 comments Page 5 of 16.
Jose said:
9 years ago
How to solve 555/60 = 37/4?
Kamlesh said:
9 years ago
@Sundar.
Your explanation is in a very simple way. Thanks.
Your explanation is in a very simple way. Thanks.
Binoy Saha said:
9 years ago
3 mins clock gains 5 sec mean? Please explain it.
Binoy saha said:
9 years ago
9 hrs 15 min. = 37/4 hrs? How please explain.
Shashi said:
9 years ago
There is no coincidence between 11 &12 hence only 11 coincidence per 12 hours.
Totally 22 coincidence per day,
Hence answer is 32.
Totally 22 coincidence per day,
Hence answer is 32.
Vinay Chik Baraik said:
9 years ago
It's given that error clock gains 5 seconds in each 3 minutes of perfect clock.
So, 3min 5sec of error clock = 3min of perfect clock.
Or, [3+(5/60)] min of error clock = 3min of perfect clock. (185s of error clock = 180s perfect clock)
Or, (37/12) min of error clock = 3min of perfect clock
Or 1 min of error clock = 3*12/37 min of perfect clock =36/37.
Now error clock moved from 7am to 4:15pm = 9hr 15min = ( 9*60 + 15 )min = 555min.
So in 555 min of error clock = (36/37)*555 min of perfect clock = 540min of perfect clock.
= (540/60) hr = 9 hr of perfect clock.
So 9hr from 7am is 4pm. Thus the answer is [B] 4 p.m.
So, 3min 5sec of error clock = 3min of perfect clock.
Or, [3+(5/60)] min of error clock = 3min of perfect clock. (185s of error clock = 180s perfect clock)
Or, (37/12) min of error clock = 3min of perfect clock
Or 1 min of error clock = 3*12/37 min of perfect clock =36/37.
Now error clock moved from 7am to 4:15pm = 9hr 15min = ( 9*60 + 15 )min = 555min.
So in 555 min of error clock = (36/37)*555 min of perfect clock = 540min of perfect clock.
= (540/60) hr = 9 hr of perfect clock.
So 9hr from 7am is 4pm. Thus the answer is [B] 4 p.m.
Akhil said:
9 years ago
7am to 4.15pm.
Total 9hrs 15min.
Total time in min= 9*60+15=555min.
For every three min, 5 seconds will be added to the wrong clock
555min /3min= 185 times
So total second added 185*5=925sec,
now convert 925sec to min=925/60= 15 min 25 sec,
so the time in original clock will be 4pm.
555min-15min, =540min=9hrs.
25 sec is neglected because clocks trigger by 5sec only after completing 3mins.
Total 9hrs 15min.
Total time in min= 9*60+15=555min.
For every three min, 5 seconds will be added to the wrong clock
555min /3min= 185 times
So total second added 185*5=925sec,
now convert 925sec to min=925/60= 15 min 25 sec,
so the time in original clock will be 4pm.
555min-15min, =540min=9hrs.
25 sec is neglected because clocks trigger by 5sec only after completing 3mins.
Navya keerthi said:
9 years ago
From 7am to 4:15pm it takes 9hrs15mins. But for ever 3mins the secs hand moves 5secs extra so so 9hrs15mins =x (3+ (5/60))because 1sec=1/60 so5secs=5/60. X=540mins. 540mins=9hrs so 9hrs from 7am is 4pm.
Akash Gupta said:
9 years ago
Another view can be:
In 3 minutes the error is 5 seconds, so every hour it gains 100 seconds.
Correct Clock ----------------------------> Wrong Clock
7 hrs ----------------------------> 7 hrs
8 hrs ----------------------------> 8hrs 100 sec
9 hrs ----------------------------> 9 hrs 200 sec
10 hrs ----------------------------> 10 hrs 300 sec
11 hrs ----------------------------> 11 hrs 400 sec
12 hrs ----------------------------> 12 hrs 500 sec
1 hrs ----------------------------> 1 hrs 600 sec
2 hrs ----------------------------> 2 hrs 700 sec
3 hrs ----------------------------> 3 hrs 800 sec
4 hrs ----------------------------> 4 hrs 900 sec ----> 4 hrs 15 minutes
In 3 minutes the error is 5 seconds, so every hour it gains 100 seconds.
Correct Clock ----------------------------> Wrong Clock
7 hrs ----------------------------> 7 hrs
8 hrs ----------------------------> 8hrs 100 sec
9 hrs ----------------------------> 9 hrs 200 sec
10 hrs ----------------------------> 10 hrs 300 sec
11 hrs ----------------------------> 11 hrs 400 sec
12 hrs ----------------------------> 12 hrs 500 sec
1 hrs ----------------------------> 1 hrs 600 sec
2 hrs ----------------------------> 2 hrs 700 sec
3 hrs ----------------------------> 3 hrs 800 sec
4 hrs ----------------------------> 4 hrs 900 sec ----> 4 hrs 15 minutes
(1)
Hassain said:
9 years ago
Anyone can tell 4.15 PM so how can you say 15 min the question is only 4?
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