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Math Help - How Many Minutes?

  1. #1
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    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


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  2. #2
    Junior Member enjam's Avatar
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    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
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  3. #3
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    Talking

    Quote Originally Posted by sharkman View Post
    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...?
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  4. #4
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    Don't apply for a watch repair job, Sharkman
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  5. #5
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    Quote Originally Posted by sharkman View Post
    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=...
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  6. #6
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    ok

    Thank you all.
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