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:
59 7 min. past 3
12
4 p.m.
58 7 min. past 3
11
2 3 min. past 4
11
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 13 of 16.

Rinkul Kamboj said:   1 decade ago
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.

Mohan said:   1 decade ago
@Mamta.

Thanks. Your explanation is good and very easy to understand.

Mamta said:   1 decade ago
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.

Puneet said:   1 decade ago
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

Chandana said:   1 decade ago
Can anybody explain clearly how 37/4hrs of wrong clk converted to 9hrs of correct clock.

C.M.Rafeek.Moothedam said:   1 decade ago
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 ?

Sundar said:   1 decade ago
@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!

Meenu said:   1 decade ago
Hi Sundar...

Please help me out.. I did not understand after this step...
[9 hr 15 min = 555 min = 33300 sec]

33300 sec :: (180/185 x 33300) sec

33300 sec :: 32400 sec

333000sec = 9 hrs 15 min :: 32400 sec = 9 hrs [:. 32400/3600 = 9]

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.

Bhaskar said:   1 decade ago
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

Poornima said:   1 decade ago
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.


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