SOLUTION: After driving 126mi, Syd found that the drive would have taken 1 hr. less time by increasing the speed by 8 mph. What was the actual speed?
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Question 786176: After driving 126mi, Syd found that the drive would have taken 1 hr. less time by increasing the speed by 8 mph. What was the actual speed? Found 2 solutions by stanbon, josmiceli:Answer by stanbon(75887) (Show Source):
You can put this solution on YOUR website! After driving 126mi, Syd found that the drive would have taken 1 hr. less time by increasing the speed by 8 mph. What was the actual speed?
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Actual DATA:
distance = 126 miles ; rate = x mph ; time = 126/x hours
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"If" DATA:
distance = 126 miles ; rate = x+8 mph ; time = 126/(x+8) hours
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Equation:
126/x - 126/(x+8) = 1 hr
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126(x+8) - 126x = x(x+8)
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x^2 + 8x - 8*126 = 0
x = 36 mph (actual speed)
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Cheers,
Stan H.
You can put this solution on YOUR website!
In the actual case:
In the other case:
By substitution:
Multiply both sides by
Use quadratic formula
and, since
The actual speed was 28 mi/hr
check:
OK
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