<PRE><B>Question 258761</B>
jacqui commutes 30 miles to her job each day. She finds that if she drives 10 miles/hour faster, it takes her 6 minutes less to get to work.
find her new speed
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Old DATA:
distance = 30 miles ; rate = x mph ; time = d/r = 30/x hrs.
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New DATA:
distance = 30 miles ; rate = (x+10) mph ; time = d/r = 30/(x+10) hrs
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Equation:
old time - new time = 1/10 hr
30/x - 30/(x+10) = 1/10
Multiply thru by 10x(x+10)
300(x+10) - 300x = x(x+10)
3000 = x^2 + 10x
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x^2 + 10x - 3000 = 0
(x+60)(x-50) = 0
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Positive solution:
x = 50 mph (old speed)
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x+10 = 60 mph (her new speed)
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Cheers,
Stan H. </PRE>