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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?

 Jun 12, 2024
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So, first let's analyze the question. 

 

Note that when Dirk finishes, Edith has ran 14km and Foley has run 9km. 

 

Well, this means Foley runs \(9/14\) as fast as Edith. 

 

So when Edith runs the entire 24km, Foley has ran \(24 (9/14) ≈ 15.43 km\)

 

Which means that Foley is \(24 - 15.43 ≈ 8.57 km \) behind Edith. 

 

So 8.57 km is our answer!

 

Thanks! :)

 Jun 12, 2024

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