SOLUTION: One a sales trip, Gail drives the 600 miles to Richmond averaging a certain speed. The return trip is made at an average speed that is 10 mph slower. total time for the round trip

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Question 202159: One a sales trip, Gail drives the 600 miles to Richmond averaging a certain speed. The return trip is made at an average speed that is 10 mph slower. total time for the round trip is 22 hours. Find Gails average speed on each part of the trip.
Answer by stanbon(75887) About Me  (Show Source):
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One a sales trip, Gail drives the 600 miles to Richmond averaging a certain speed. The return trip is made at an average speed that is 10 mph slower. total time for the round trip is 22 hours. Find Gails average speed on each part of the trip.
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To-Richmond DATA:
distance = 600 miles ; rate = x mph ; time = d/r = 600/x hrs
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From-Richmond DATA:
distance = 600 miles ; rate = x-10 mph ; time = d/r = 600/(x-10) hrs
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Equation:
time + time = 22
600/x + 600/(x-10) = 22
300/x + 300/(x-10) = 11
300x - 300*10 + 300x = 11x(x-10)
600x -3000 = 11x^2 - 110x
11x^2 -710x + 3000 = 0
x = 60 mph
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Cheers,
Stan H.