Question 1004984: the distance d, in feet required for a vehicle traveling at r mi/h to come to a stop is given approximately by d=0.05r^2 + r. If an automobile in a 55 mi/h speed zone is required 240 feet to stop, was its speed within the legal limit?
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! the distance d, in feet required for a vehicle traveling at r mi/h to come to a stop is given approximately by d=0.05r^2 + r.
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If an automobile in a 55 mi/h speed zone is required 240 feet to stop, was its speed within the legal limit?
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Solve for "r"::
0.05r^2 + r - 240 = 0
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Use the Quadratic Formula to get::
r = [-1 +- sqrt(1-4*0.05*-240)]/(2*0.05)
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r = [-1 +- 7]/0.1
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Acceptable answer::
r = [6/0.1] = 60 mph
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Answer: No
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Cheers,
Stan H.
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