SOLUTION: Please help me with this problem: Helped by a strong jet stream, a Los Angeles-to-Boston plane flew 10% faster than usual and made the 4400 km trip in 30 minutes less time than usu

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Question 26010: Please help me with this problem: Helped by a strong jet stream, a Los Angeles-to-Boston plane flew 10% faster than usual and made the 4400 km trip in 30 minutes less time than usual. At what speed does the plane usually fly?
Thank you!
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
Usual Flight Data:
distance=1400; rate=x mph; time=d/r=1400/x hrs.
Faster Flight Data:
distance=1400; rate=1.1xmph; time=d/r=1400/1.1x
EQUATION:
Usual time-Faster time= 2/3 hr
(1400/x) - (1400-1.1x)= 2/3
Divide by 1400 to get:
1/x - 1/1.1x =1/2100
(1.1x-x)/(1.1x^2)= 1/2100
0.1x/1.1x^2= 1/2100
0.1/1.1x=1/2100
1.1x=210
x=190.90 (usual speed of the plane)
Cheers,
Stan H.