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Three runners, Dirk, Edith, and Foley all start at the same time for a $24$ km race, and each of them runs at a constant speed. When Dirk finishes the race, Edith is $10$ km behind, and Foley is $15$ km behind.  When Edith finishes the race, how far behind is Foley, in km?

 Jan 29, 2025
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When Dirk finishes, Edith has run 14 km and Foley has run 9 km

 

So ....  his rate to  her rate =  9/14

 

When  she finishes, Foley has run   (9/14 )* 24 km

 

So he is   24 -  (9/14) * 24  =  24 ( 1 - 9/14)  =  24 * ( 5/14)  ≈  8.57 km behind

 

cool cool cool

 Jan 30, 2025

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