Aptitude - Clock - Discussion

Gain:
3 minutes 5 sec,
15 minutes 25 sec,
30 minutes 50 sec,
60 min( 1 hour) 100 sec.

Then, 7 to 4:15 - 9 hours 15 minutes.
Per hour 100 sec= 900.
And 15 minutes 25 sec.
Total - 925 sec.
925 sec ÷ 60 = 15 minutes.
(15 mins is extra).
9 hours 15 - 15 minutes 9 hours.
7 AM to 4 PM (9 hours).
So, the answer is 4 PM.

For 3 mins it gains 5 seconds.

Then for 925 minutes (9hr 15 min) it gains 15 mins 25 seconds.

So, subtract 15 mins 25 seconds from 4:15.
We will get 3:59:35 which is 59* (7/12) mins past 3.

Thank you everyone for explaining the answer.

It gains 5 seconds in 3 minutes.

3min = 5seconds
3min = 1/12 min
1min = 1/36 min

Let correct watch shows time which is x min ahead of 7 am.

Then minutes gained by faulty clock = x/36minutes.

So, the faulty clock is ahead of 7 am by (x + x/36)min or 37x/36 min.

but in question, it is given faulty clock shows 4.15 pm which is (9*60+15)min or 555min ahead of 7 am.

So,
37x/36 = 555

x = 540min or 9 hrs

So, the correct time is 7 am + 9hr = 4 pm.

Note: We have to calculate the time gained by the faulty clock in terms of the correct clock not in terms of the faulty clock time given in the question

3 min - 5 sec.
30 min - 50 sec.
60 min - 100 sec. [ 1 hour - 100 sec]
9 hours - 900 sec [900 sec = 15 min ].

The clock is showing 4:15 and we know that it gained 15 mins
Therefore it must the real-time is 4 pm.

The right answer is option A.

Gained time = 925 secs ==> 15 mins and 25 secs.

From 4.15 - 15 mins ==> 4 (only subtracting the 15mins).

From 4 - 25 secs ==> converting in fraction (25/60) ==> need to subract 25 sec ie: remaining of 35/60,

So,3 hrs and 59 mins and 35/60 ==> 59 mins 7/12 past 3. So, the answer is A.

9 hr 15 min= 555min.

Watch gain 5 sec in 3 min so, we will check how many minutes gain 5 sec.

So, 555/3= 185min
185 min gains how many sec=185 multiplies with 5 = 925 sec.

And convert 925sec into min= 15.41 min( gain a minute, so we have to minus it from the time shown)

Now 4.15 was showing on the clock now minus 15min from it= 4pm.

5sec gains in 3min.

5sec =3 min.
Multiply with 20.

100 sec gains in 60min(100sec = 60min).
Then 300sec = 180min.
Converting 300 sec into min is 5min.
180min is 3 hrs.
So it gains 5min in 3hrs.
We know that from 7 to 4 .15min is 9hrs 15min.
It gains 5min in 3hrs then for 9hrs it gains 15min so subtract 15 min from the time.

Then the answer is 4'pm.

If the clock gains 5sec for every 3mins it travels 9hrs and 15mins i.e., 9.25hrs.
Let the actual clock goes 'x' 3mins.

Then the clock which gains 5 secs for every 3 mins will go (3mins)x + (5secs)x =9.25hrs
=> (3+ (5/60))x = 9.25*60.
So x= 180mins,
i.e., x=3hrs,
So the actual clock goes 3x i.e., 9hrs.
So, 9hrs from 7 a.m. is 4 p.m.