SOLUTION: A car traveled 468 mi at a certain speed. If the speed had been 13 mph faster, the trip could have been made in 3 hr less time. Find the speed.
Question 839777: A car traveled 468 mi at a certain speed. If the speed had been 13 mph faster, the trip could have been made in 3 hr less time. Find the speed. Answer by stanbon(75887) (Show Source):
You can put this solution on YOUR website! A car traveled 468 mi at a certain speed. If the speed had been 13 mph faster, the trip could have been made in 3 hr less time. Find the speed.
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Slower DATA:
distance = 469 miles ; rate = r mph ; time = 469/r hrs
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Faster DATA:
distance = 469 miles ; rate = r+13 mph ; time = 469/(r+13) hrs
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Equation:
slower time - faster time = 3 hrs.
469/r - 469/(r+13) = 3 hrs
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469r + 469*13 - 469r = 3r(r+13)
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3r^2 + 39r -469*13 = 0
r = 39.05.. mph
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Cheers,
Stan H.
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