SOLUTION: Bianca travelled 1200km.if her average speed had been 5 more km per hour,she could have made the trip in 12 hours less time.find bianca s average speed
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Question 919187: Bianca travelled 1200km.if her average speed had been 5 more km per hour,she could have made the trip in 12 hours less time.find bianca s average speed
Found 2 solutions by stanbon, josmiceli:
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
Bianca travelled 1200km.if her average speed had been 5 more km per hour,she could have made the trip in 12 hours less time.find bianca s average speed
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Original DATA:
dist = 1200 km ; rate = x mph ; time = 1200/x hrs
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Adjusted DATA:
dist = 1200 km ; rate = x+5 mph ; time = 1200/(x+5) hrs
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Equation:
orig time - adj time = 12 hrs
1200/x - 1200/(x+5) = 12 hrs
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1200x + 1200*5 - 1200x = 12x(x+5)
----
60000 = 12x^2 + 60x
x^2 + 5x - 5000 = 0
----
(x-68.25)(x+73.25) = 0
Positive solution:
x = 68.25 km/hr
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Cheers,
Stan H.
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Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
Let = Bianca's average speed
Let = her time in hrs to travel 1200nkm
----------------------
(1)
(2)
-----------------------------
(2)
(2)
and
(1)
(2)
(2)
(2)
(2)
(2)
Complete the square
(2)
(2)
(2)
(2)
Take the square root of both sides
(2) ( only the positive root works here )
(2)
(2)
Her average speed is 20 km/hr
check:
(1)
(1)
(1)
and
(2)
(2)
(2)
(2)
OK
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