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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?

 May 17, 2024
 #1
avatar+129771 
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When Dirk finishes, Edith has run 14km  and Foley has run 9 km

 

So Foley runs  9/14  as fast as Edith

 

When Edith has run 24km, Foley has run  24 (9/14)  ≈  15.43  km

 

So Foley is   24 - 15.43  ≈  8.57 km behind

 

cool cool cool

 May 17, 2024

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