Question 344600: Two trains leave at the same time from the same station, one traveling due south and the other traveling due east. The eastbound train is traveling 20 miles an hour faster than the southbound train. After 4 hours the trains are 400 miles apart, what is the rate of each train.
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! Two trains leave at the same time from the same station, one traveling due south and the other traveling due east. The eastbound train is traveling 20 miles an hour faster than the southbound train. After 4 hours the trains are 400 miles apart, what is the rate of each train.
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East train DATA:
rate = x+20 ; time = 4 ; distance = 4x+80 miles
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South train DATA:
rate = x mph ; time = 4 hrs ; distance = 4x miles
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Equation:
distance^2 = [(4x+80)^2 + (4x)^2]
400^2 = 32x^2 + 640x + 6400
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x^2 + 20x - 4800 = 0
(x-60)(x+80) = 0
Positive solution:
x = 60 mph (rate of south train)
x+20 = 80 mph (rate of east train)
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Cheers,
Stan H.
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