Question 1094295
Ryan and Nelson should be at the 400th feet together after 30 seconds.
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Collect data..
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Nelson running at 6ft/s is 60ft ahead of Ryan.
Ryan then runs on speed xft/s and catches up with Nelson at 400ft after 30sec.
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Process data..
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Assuming Nelson had been running on constant speed 6ft/s from start to finish, then he's going to cover the entire 400ft track in (400/6)secs 
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When he'as 30 secs to go, he'll've (6*400*30/400)fts to cover = 180fts
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Nelson is 60ft behind at that time, meaning he'll've 240fts to cover
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Equating to satisfy objective, we'll've:
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30 seconds = 
Ryan's remaining distance/his speed
= Nelson's remaining distance/his speed
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{{{ 240/x }}} = {{{ 180/6 }}}
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240/x = 30
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x = 240/30 = 8
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Give out information..
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While Nelson runs constantly at 6ft/s, Ryan should increase his speed and run at 8ft/s so that they both finish the track together within the last 30 seconds.
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Your friend,
Francis.