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October 31, 2014

October 31, 2014

Posted by **jack** on Monday, August 23, 2010 at 4:15am.

- math -
**drwls**, Monday, August 23, 2010 at 5:29amLet V be the speed of the slower runner. Let his (or her) time to run 1000 m be T. The faster runner's speed is V + 5 (in meters per second). Here is what you know:

(V+5)(T+10) = 1500

V*T = 1000

V*T + 5T + 10V + 50 = 1500

5T + 10V = 450

5000/V + 10V = 450 (after substituting 1000 for V*T)

V^2 -45V + 500 = 0

(after multiplying boith sidesw by V and dividing by 10)

(V-25)(V-20) = 0

V = 20 m/s, V+5 = 25 m/s, T = 50s would be one answer

V = 25 m/s, V+5 = 30; T = 40 s would be another answer.

It sounds fishy to me that there are two possible sets of answers. The speeds are also faster than humans can run.

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