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Audrey rode her bike to school at a rate of 12mi/hr. She rode back at a rate of 8mi/hr. How far is it to school if the round trip takes 1 hour?

 Jun 12, 2018
 #1
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Let us have d= the distance from home to school. Then the time at 12mi/hr is 5d because 12/60=1/5. Similarily 8/60=2/15 so it takes 15/2*d. Adding the times gives us 12.5d=60 so d=4.8mi. Thus it takes 4.8mi to school.

 Jun 12, 2018
 #2
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Let the distance = D

 

Average speed = Distance travelled / Time

Time = Distance / speed

D/12  +  D/8 = 1 hour, solve for D

[2D  +  3D]  / 24 = 1 hour                 cross multiply

5D = 24                                                 divide both sides by 5

D = 24/5

D = 4.8 miles - the distance from her home to shchool.

 Jun 12, 2018
 #3
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thank yousmiley

 Jun 12, 2018

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