Aptitude - Clock - Discussion

Why do you get 3 mins in every 3mins 5 secs of the time? :(.

@Praveen you got simple & sweet logic. My answer was A.
Here it is:

(9*60)+15=540+15=555min.

(555/3)*5=925 seconds=925/60min=15min and 25sec.

4:15pm)-(15min and 25 sec)=3:59:35pm.

35 sec in min= 35/60=7/12min.

59(7/12).

But you got simple one and correct too.
Thanks buddy!

The problem is with the calculation of 9hr 15min=555 minutes. This value is associated with the erroneous clock. You need to convert it for the true clock. As per data, we can write,

3 mins in the true clock equals 3 min 5 seconds (3+5/60 or 37/12 minutes) in erroneous clock. Thus we have

37/12 mins of erroneous clock equals 3 mins of true clock.
1 mins of erroneous clock equals (3*12/37) mins of true clock.
555 mins of erroneous clock equals (3*12*555/37)=540 mins of true clock.

540 minutes = 540/60 hours = 9 hours. The actual time is (7+9) hours = 16 hours = 4P.M.

Time from 7 a.m. to 4.15 p.m. = 9 hrs 15 min. = 37/4 hrs.

3 min. 5 sec. of this clock = 3 min. of the correct clock.

37/720hrs of this clock = 1 /20hrs of the correct clock.
(Convert into hours in both sides).

(37/720)x 1 hrs of this clock = 1 /20hrs of the correct clock.

1 hrs of this clock = (1 /20)* (720/37) hrs of the correct clock.

(37/4) hrs of this clock = (1 /20)* (720/37)*(37/4) hrs of the correct clock.
i.e. = 9 hrs.

i.e. The correct time of the clock is 4 p.m.

Total hours between 7 a.m to 4.15 p.m is 9 hrs 15 min.

3 min gains 5 seconds.
15 min gains 25 seconds.
60 min gains 100 seconds.
i.e. 1 hour gains 100 seconds.
i.e. 9 hours gains 900 seconds.
i.e. 9 hours 15 min gains 900+25 = 925 seconds.
Now, 9 hours 15 min = 33300 seconds.

The correct time is = 33300 - 925 = 32375 seconds.
= 32375/3600 .
= 8.99 hr = 9 hr.

Therefore the correct time is 4 p.m.

Four clocks rang 18 24 40 60 min respectively. If four clocks will rang at 5 o'clock then when will they rang again at same time.

How 55 minute spaces are gained by the minute hand in 60 minutes?

What is mean by "when the watch indicated quarter past 4 o'clock"?

Dear Asha,

The clock set right at 7.00 am but thereafter it gains 5 seconds every 3 minutes, hence we have to calculate the correct time.

@Asha.

Given that the "clock was set right at 7:00am". So, I think there is no error in time further. Hence at 4:00pm the time is 4:00pm itself.

Please suggest me if I'm wrong.