<PRE><B>Question 132847</B>
The speed of sound in air is 1100 feet per second. The speed of sound in steel is 16500 per second. Robin, one ear pressed against the railroad track, hears a sound through the rail six seconds before hearing the same sound through the air. To the nearest foot, how far away is the source of that sound?
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Time difference = 6 seconds
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Rail DATA:
Distance = x ft ; Rate = 16,500 ft/sec ; Time = d/r = x/16500 sec
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Air DATA:
Distance = x ft ; Rate = 11000 ft/sec ; Time = d/r = x/11000 sec
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EQUATION:
air time - rail time = 6 seconds
x/11000 - x/16500 = 6
(16500x - 11000x) = 6(11000*16500)
5500x = 6*11000*16500
x = 198,000 ft.(distance the train was when it initiated the sound heard 
by Robin)
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Cheers,
Stan H.</PRE>