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How to add/change to fraction form: 5 hours 36 min 7 s + 8 hours 28 min 9 s=?

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mint18 | Student, Grade 9 | (Level 1) eNoter

Posted August 2, 2013 at 9:44 PM via iOS

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How to add/change to fraction form: 5 hours 36 min 7 s + 8 hours 28 min 9 s=?

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tjbrewer | Elementary School Teacher | (Level 2) Associate Educator

Posted August 2, 2013 at 10:36 PM (Answer #1)

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There are two ways to go about this:  Add the times first, and then convert the sum to a fraction; or Convert the times first into fractions then, add them together.  It is simpler though, to add the times first. 

We add the seconds first `7+9=16` 16<60, so no regrouping needed
We add the minutes and get `36+28=64` 64>60 so we need to regroup `64-:60=1r4=1h 4min` We keep the 4 minutes, and add the 1 hour to the hours column
Finally we add the hours: `5+8+1=14`
That gives us a grand sum of 14 hours, 4 min 16 sec.

1 hours is 60 minutes, that means each minute is 1/60 of an hour.  There are 60 seconds in each minute so 1 sec is 1/60 of 1/60 of an hour or 1/360 of an hour.  We apply these calculations to our sum, we get `14+4/60+16/360` To add our two fractions together we need a common denominator`4/60xx60/60=240/360` So `240/360+16/360=256/360`` `
Then we reduce the fraction `256/360=32/45`

The final value is `14 32/45 hours`

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