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Alice cycles to Carla's house at 12 miles per hour and returns by car at 36 miles per hour. If the round trip took 1 hour, how far from Carla does Alice live?

Guest Oct 27, 2017
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 #1
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+2

Let the time she travels at 12 mph  = x minutes and if she trqvels back at 36 mph.....since this is 3 times as fast...it must take her x / 3 minutes  to return

 

So

 

x +  x/3  =  60     mutiply through by 3

 

3x + x  =  180

 

4x  = 180   divide by 4

 

45  = x

 

So....she travels   45/3 minutes = 15 minutes at 36 mph

 

And since  15 minutes = 1/4 hr......the distance is

 

Rate x Time  =  36mph  x 1/4 hr  =  9 miles

 

 

 

cool cool cool

CPhill  Oct 27, 2017
 #2
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+1

Let the distance between Alice and Carla's house =D
Time=Distance / Speed
D/12 + D/36 =1, solve for D
D = 9 miles the distance between the 2 houses.

Guest Oct 27, 2017

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