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Express the following as a unit rate.  If necessary round to the nearest tenth.  100...

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matrixara | eNoter

Posted June 18, 2010 at 8:49 AM via web

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Express the following as a unit rate.  If necessary round to the nearest tenth.  100 miles in 2.5 hours.

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pohnpei397 | College Teacher | (Level 3) Distinguished Educator

Posted June 18, 2010 at 8:51 AM (Answer #1)

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You can express this as 40 miles per hour.

We know that we have gone 100 miles and that it took us 2.5 hours to go that distance.  All we have to do to find out how many miles per hour this is is to divide the number of miles gone by the number of hours it took to go that distance.

So we divide 100 by 2.5 and we get 40.

One way to remember what you have to do here is to realize that the word "per" means "divided by."  So if you have miles per hour, you take the number of miles (100) and divide them by the number of hours (2.5) and get miles per (divided by) hour.

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hala718 | High School Teacher | (Level 1) Educator Emeritus

Posted June 18, 2010 at 9:41 AM (Answer #2)

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100 miles in 2.5 hours

We need to find the speed (or how many miles in an hour)

The speed S = distance D / time T

       S = 100/2.5 = 40 mile/hour

Or if we use the ratio properties:

100 miles in 2.5 hour

  x   miles in 1 hour

2.5 * x = 100* 1

 ==> x= 100/2.5 = 40 m/h

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krishna-agrawala | College Teacher | Valedictorian

Posted June 18, 2010 at 11:22 AM (Answer #3)

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Unit rate in this case will be in units of miles per hour. This can be calculates as follows by dividing the the total distance covered by total time taken to cover the distance.

The total distance covered is 100 miles, and the total time taken for this is 2,5 hours. Therefore, speed in units of miles per hour is 100 divided by 2.5, that is 40 miles per hour.

This can be expressed mathematically as:

Speed = (Distance covered)/(Time take)

= 100/2.5 = 40.0 miles per hour.

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neela | High School Teacher | Valedictorian

Posted June 18, 2010 at 12:14 PM (Answer #4)

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100 miles in 2.5hrs is normally expressed as 100mile/2.5hrs = 100 miles / (5/2 hrs) = (200/5) miles per hour = 40 miles per hour. We say how fast a moving vehicle  or an object is and say the speed in miles per hour.

If the unit of time is considered minutes, the speed is 100miles /(2*5*60 minutes) = (100*1760 yards*3feet)/(2.5*60 minutes) =  1173.3333 ft/minute

If the unit of time is  in seconds, the speed is = 100*1760*3 feet)/(2*5*60*60 seconds) =  19.5556 feet/second.

 

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