Please answer in detail.?

Question

A watch goes slow by 5 minutes per hour . It was set right at 7:00 in the morning.What is the correct time,when it shows 12:00 noon the same day?

Answer 1

The first 2 answers don't help, the next 2 are wrong and the next 2 have grasped the problem but don't give an exact answer.

The correct time when the watch shows midday is 12:27 and 16.363636 seconds.

In summary terms it's 300 divided by 55 multiplied by 60 and converted from a decimal number into time format.

A more detailed explanation follows, hope it makes sense...

There are 60 minutes in an hour but the faulty watch is slow by 5 minutes each hour so the watch is only registering 55 minutes per hour.

To put it another way, the watch is running at 55/60ths of the correct speed.

Between 7am and midday there are 300 minutes (5 hours, 60 minutes per hour, 5 x 60 = 300). But this watch is slow.

To work out how many minutes have really elapsed means taking into account the slowness of the watch so we need to divide 300 (the total time shown by the watch) by 55 (the number of minutes per hour according to the watch) and then multiply this by 60 (the number of minutes in a real hour),

This gives a figure of 327.272727... which is the correct amount of time that has elapsed. Or to put it another way, the correct time is 327.272727 minutes after 7am.

This is fairly meaningless so it needs to be converted into a sensible time format. For now we'll take the 327 minutes and deal with the 0.272727 bit later.

327 minutes is the same a 5 hours 27 minutes (there are 300 minutes in 5 hours - 5 x 60 = 300).

5 hours after 7am is midday and then there's the 27 minutes as well the time is 12.27pm.

But... there's the 0.272727 of a minute to take into account. This needs to be converted into seconds (0.27 of a minute is not the same as 27 seconds, 0.27 is a little over a quarter so the answer we arrive at has to be a little over a quarter of a minute).

There are 60 seonds in a minute so to convert our decimal (0.272727) into seconds we need to multiply by 60/100ths - this is the same as multiplying by 60 and dividing by 100 or multiplying by 0.6 (same thing).

0.272727 x 0.6 = 16.363636. These are the number of seconds to be added to the time we previously calculated.

The answer is therefore 12:27 and 16.363636 seconds.

Answer 2

This one's a bit tricky. At first glance, one might simply say that the watch looses 5 min / hour, so since 5 hours have elapsed, the watch must be 25 minutes slow, so the correct time is 12:25.

This is incorrect.

Consider....during the first hour of "real" time, the watch is slow, so when it's really 8:00 AM, the watch reads 7:55. Similarly, when the second hour passes (now the real time is 9:00), the watch reads 8:50.

So, when the real time is 12:00, the watch will read 11:35...it has indeed lost 25 minutes over 5 hours, but we now have to wait until the watch reads 12:00. How long will it take the slow watch, currently displaying 11:35, to reach 12:00? A tad MORE than 25 real minutes, because it's slow!!

So.....when the watch reads 12:00, the real time is 12:25 PLUS the additional delay incurred during the last 25 minutes.

Since the watch looses 12% (5 / 60), it's lost 3 minutes during the last 25 "real" minutes.

The real time when the watch reads 12:00 PM is 12:28.

Answer 3

Well these answers so far are ALMOST right. 12:25 would be right except that the watch doesn't run right on time and then just lose 5 mins right at the end of the hour. It is slowly dropping them all the way so you would solve like this:

(12-7)*5=5*5=25, then you go 5/60=1/12 meaning it loses 1min every 12 mins, so by 12:25 it really would have lost another 2 mins approximately. In other words when the watch says 12:00 it really is about 12:27

Answer 4

(12 - 7) * 5 = 5 * 5 = 25 minutes slow

True Time : 12:25 pm

Answer 5

Time to do your own homework. ;-)

If we give you the answer, you do not learn anything.

How many hours have elapsed between 7am and noon?
We know it's slow by 5 min/hr

Do the math.

Answer 6

at 5min/hr

12-7=5
therefore 5x5=25mins

the correct time would be 25mins plus 12

12:25 pm

Answer 7

I hate math too. Especially problems like this. I don't blame you for not wanting to do it.