Aptitude - Clock - Discussion

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]

As given in question we know that.

A watch gains 5 seconds in 3 minutes.

Its means covert 3 min into seconds 4.

(3 x 60) = 180 sec (1 min = 60 sec).

Question tells 5 seconds gain.

It means for 180 sec it will become 180 + 5 = 185 seconds.

Right time is 180 seconds wrong time is 185 seconds.

Difference between true time and wrong time is 7 am to 4. 15 pm is 9 hours 15 min.

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

For 180 - 185.

? - 555.

(180 x 555) /185 = 540 in sec convert into min I. E 540/60 = 4 min.

3min 5sec = 3min.
6min 10sec = 6min.

Similary 1hr = 1hr 1min 40sec.

Calculation:

6*10min = 6*10min 10*10sec
60 min = 60 min 100 sec(61min 40 sec)
So, total gain 1hour = 1min 40 sec.

Time between 7 am to 4.15 pm= 9hr 15 min.

In 9hr 15 min time gain will we 15min because;

9*1min 40 sec=> 9min + 360sec =>9 min + 6min =>15min.

So the correct time in the clock is 4 pm.

And gain in remaining 15 min =25sec (5*5).

25 sec can be neglected.

Hence the correct answer option B.

3min 5sec = 3min.
6min 10sec = 6min.

Similary 1hr = 1hr 1min 40sec.

Calculation:

6*10min = 6*10min 10*10sec
60 min = 60 min 100 sec(61min 40 sec)
So, total gain 1hour = 1min 40 sec.

Time between 7 am to 4.15 pm= 9hr 15 min.

In 9hr 15 min time gain will we 15min because;

9*1min 40 sec=> 9min + 360sec =>9 min + 6min =>15min.

So the correct time in the clock is 4 pm.

And gain in remaining 15 min =25sec (5*5).

25 sec can be neglected.

Hence the correct answer option B.

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.

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 ?

Hai friends,

I think we have to find the error.
Clock gains 5 sec in 180sec of actual clock.

So,

The error is 5 sec in 185 sec. in errored clock.
In error clock. The passed time is 9H and 15min.

Which is equal to 555 min.(9 * 60 + 15).
Thus it is 33300 in sec.

We have 5 sec error for every 185 sec.
So for 33300 sec we have 900 sec error. (33300 * 5/185).

Error in min. is 15 (900 sec / 60).

So the actual time is 4:00pm (4:15 - 15 min).

I hope you all understood.

Given in question that in every 3 minutes 5 sec = 185 sec. increases, so the wrong time we get 4:15.

Now we have to get the correct time, for this first take the wrong time.
Given it is 4:15 which is started from 7 in morning, so that's mean it is 9 hr 15 minutes.
555 min = 333000 sec.
Now for the correct clock,
It will be 3 minute = 180 seconds.

So, correct time can be written as (180/185)*333000 sec. = 32400 sec.
which is equal to 9 hr so the answer is 4 p.m.

Actually Sundar's explanation is correct.

Don't get confusion. The question is about two clocks (accurate clock and the error clock). So many of you confused.. 59 7/12 past 3 is wrong because, you are considering only one clock.. you went wrong while dividing 555 minute by 3.. in reality... 555 minutes are passed in ERROR CLOCK,

So you must divide 555 by 3 min 5 seconds (OR 555*60=33300 seconds divided by 3*60+5=185 seconds) Then you will get the right answer.

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.