Aptitude - Clock - Discussion

How we got 4. 15 pm and 3 min. 5 sec. Of this clock = 3 min. Of the correct clock? Please I'm unable understand.

In 3 MIN = The clock gains 5 sec.
in 60 min(3 * 20) = clock gains 100 sec(5 * 20)
= i.e 100/60 min
= 5/3 min
So , If correct clock shows 1 hour=den da wrong clock shows 1 hr 5/3 min..
i.e
1 hr=1 hr 5/3 min
=1 * 5/(3*60) hour (convert to hour)
=37/36 hour

But we need to do reverse..
i.e
37/36 hrs(in wrong clock) = 1 hr
1 hour in wrong clock = 1/(37/36)=36/37 hr

9hr 15min=37/4 hrs

So
37/4 hours in wrong clock =36/37 * 37/4
= 9
So 7 a.m + 9 hrs= 4 pm ....

I hope every1 got it...

I have a different view for this question..
Its is straight from the question that the watch gains 1/12 min( 5 seconds) for every 3 min.
Den from 7 am to 4.15 PM its totally 555 min...

Now watch would have totally gained (1/12)*555/3= 15 5/12 min.
Therefore actual time would be (4.15 PM - 15 5/12 min) 3PM 59 7/12 min

In 3 min gain is 5 sec
so in 15 min gain is 25 sec
and in 60 min gain will be 100 sec
so in 9 hours and 15 min gain will be
925 sec i.e. 925/60 = 15 5/12
so correct ans is 3pm 59 7/12 min
Tell me whats wrong in my explanation ?

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.

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

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.

@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!

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 ?

Can anybody explain clearly how 37/4hrs of wrong clk converted to 9hrs of correct clock.