SOLUTION: It is four o'clock now. How many minutes will pass before the minute hand and hour hand of the clock are pointing to the exact same place? (Hint: it is not 20 minutes, because by t

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Question 717922: It is four o'clock now. How many minutes will pass before the minute hand and hour hand of the clock are pointing to the exact same place? (Hint: it is not 20 minutes, because by the time the minute hand points to the 4, the hour hand will have crept ahead a little.)
Answer by Edwin McCravy(20060)   (Show Source): You can put this solution on YOUR website!
There are 60 minute-marks around the face of a clock.

The speed of the minute hand is 60 minute-marks per 1 hour,

or  or 

The speed of the hour hand is 60 minute-marks per 12 hours.

or  or  or 

At 4:00 the hour hand has a 20 minute-mark head start on the hour
hand, so the minute hand's catch-up rate is 60-5 or .  
Since time = , the minute hand will catch up to the hour hand
in  hr which reduces to  of an hour which is  minutes
or  minutes, or  minutes

That's  21 minutes and  seconds. 

Edwin
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