SOLUTION: If you had driven one mile at 30 mph, how fast must you drive the second mile so your average speed for the trip is 60mph. Hint: The answer is not 90 mph.

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Question 170053: If you had driven one mile at 30 mph, how fast must you drive the second mile so your average speed for the trip is 60mph.
Hint: The answer is not 90 mph.
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
If you had driven one mile at 30 mph, how fast must you drive the second mile so your average speed for the trip is 60mph
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1st mile DATA:
distance = 1 mile ; rate = 30 mph ; time = d/r = 1/30 hr
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2 mile DATA
distance = 2 miles ; rate = 60 mph; time = d/r = 2/60 = 1/30 hr
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2nd mile Information
distance = 1 mile ; time = (1/30)hr - (1/30)hr = 0 hrs
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You cannot average 60 mph by driving the 2nd mile at any speed.
The time required to drive the 2 miles at 60 mph is the same
as the time required to drive the 1st mile at 30 mph. After
the 1st mile you have used up all the time you need.
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Cheers,
Stan H.