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Intern
Joined: 04 Jun 2004
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Svetlana runs a 20 mile race. At what time did she finish [#permalink]
 19 Aug 2004, 21:21
Svetlana runs a 20 mile race. At what time did she finish the race?
1. She started the race at 8:05AM and her average speed for the first 10 miles of the race was 8 miles per hour.
2.She had completed half of the amount of running time at 9:20AM and had completed 80% of running time at 10:05AM.
One explanation I saw was that the answer was C, but
I'd like to know why it couldn't just be B instead, since, if we determine
that 30% of the running time consisted of 45 mins., we can just determine what 20% of the running time would be and add it to the 80% time point.
?
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Director
Joined: 20 Jul 2004
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Yes, I think it should be B.
30% = 3/4
50% = 5/4
Final Time = 9:20 + 1:15 = 10:35 AM
(A is useless, since it just talks about first half distance. It doesn't say if she varied her ave speed in the next half distance.
In the above solution, we've assumed that she runs at her ave speed whole through the race.)
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Senior Manager
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I would say E. The assumption that she runs at average speed is not stated.
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