Aptitude - Clock - Discussion

Time from 7 a.m to 4:15 p.m = 9hr 15min. Please explain the above line. how to get the answer "9 hrs 15 min"?

But it is stated in the question that the wrong clock gains 5 sec in 3 mint. Does it mean that it is 3 mint 5 secs fast?

I'm confused. Someone please explain it for me.

Time from 7 a.m to 4:15 p.m = 9hr 15min.

= 9*60min+15min = 555min.

3min 5sec clock(wrong) = 3min (correct).

3*60sec+5sec = 3*60 sec.

185sec = 180sec.

If 1 sec = 180/185 sec.

Then 555 min = (180/185)*555.

= 540 min.

= 9hr.

Than correct answer is 7a.m +9hr = 4p.m.

Can anyone tell the reason behind the multiplication [1/20*720/37*37/4]?

Why they are multiplying the values at last to get 9 hrs? I am confused here. Rest all is clear. Please help me.

Still I'm confused how the 37/720 hrs is equal to 1/20 hrs.

FAULT CLOCK CORRECT CLOCK

7am < ---------------- > 7am
8am 100 sec < ------------ > 8am
9am 200 sec < ------------ > 9am

So on..

4pm 900 sec < ------------ > 4pm

So 4pm 900 sec = 4pm 900/60 min = 4pm 15 min.

Therefore when Fault clock shows the time 4pm 15 min the Correct clock will show 4pm.

So correct answer is 4pm.

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.

x+((x*5)/(3*60))=555*60.
Find x?

x is the seconds between 7am and correct time.
555 is minutes between 7am and wrong time.

Find x and convert to hrs getting x as 32400 sec.
Then converted to hrs.

32400/3600= 9 hrs.

7am+ 9hrs=4PM.

For 9 hrs its 9x60=540 minutes.
In 540 minutes (540/3)=180 i.e 180 times 3 minutes are there for each 3 minute it is 5 second then 180x5=900 seconds 900/60=15 minutes, which is extra to be subtracted from 4.15 pm. So 4 is the answer.