# How Many Minutes?

• Aug 26th 2009, 06:40 AM
sharkman
How Many Minutes?
A watch loses 0.15 seconds every minute. How many minutes will it lose in one day.

My work:

There are 24 hours in one day.
There are 60 minutes in one hour.
So, 24 x 60 = 1440 minutes in one day.
There are 60 seconds in one minute.
So, 1440 x 60 = 86,400 seconds in one day.
0.15/86,400 = 0.60/x
(86,400)(0.60) = (x)(0.15)
51,840 = x(0.15)
51,840/0.15 = x
345,600 = x
345,600/86,400 = x
4 minutes = x

OR

Is it this way:

86,400/0.15 = 576,000

576,000/1440 = 400 minutes

• Aug 26th 2009, 07:16 AM
enjam
1440 mins / day
- if the watch lost 1 second per minute, it'd lose 1440 seconds in a day
The watch loses 0.15 x 1440 seconds in a day
So it loses 216 seconds in a day = 3.6 minutes
• Aug 26th 2009, 07:27 AM
stapel
Quote:

Originally Posted by sharkman
0.15/86,400 = 0.60/x

This equation has units of "[no unit] per minute" on the left-hand side. What do you mean by this?

Also, where did the "0.60" come from? What does this mean?

Instead, try working with the units. You have 0.15 sec/min and 86,400 sec/day, and are wanting to find sec/day. So it would probably be wiser to leave the "per day" as "minutes per day". Then you would have:

(0.15 sec/min)*(1440 min/day)

What units will be left...? (Wink)
• Aug 26th 2009, 07:33 AM
Wilmer
Don't apply for a watch repair job, Sharkman (Itwasntme)
• Aug 26th 2009, 08:15 AM
Quote:

Originally Posted by sharkman
A watch loses 0.15 seconds every minute. How many minutes will it lose in one day.

My work:

There are 24 hours in one day.
There are 60 minutes in one hour.
So, 24 x 60 = 1440 minutes in one day.
There are 60 seconds in one minute.
So, 1440 x 60 = 86,400 seconds in one day.
0.15/86,400 = 0.60/x
(86,400)(0.60) = (x)(0.15)
51,840 = x(0.15)
51,840/0.15 = x
345,600 = x
345,600/86,400 = x
4 minutes = x

OR

Is it this way:

86,400/0.15 = 576,000

576,000/1440 = 400 minutes

Neither is correct . 0.15 seconds is lost every minute , NOT every second .
SO you know there are 1440 minutes per day .
1 mins - lost 0.15 sec
1440 mins - lost ?

Therefore it would be 1440x0.15=...
• Aug 26th 2009, 03:46 PM
sharkman
ok
Thank you all.