Question 957728: The rate of a jet stream is 300 milers per hour. Traveling with the jet stream, an airplane can fly 4200 miles in the same amount of time at it takes to fly 1400 miles against the jet stream. what is the airplanes average rate in calm air?
Answer by josgarithmetic(39616)   (Show Source):
You can put this solution on YOUR website! Assign variables.
r, the airplane's rate if no jet stream.
w, the rate of the jet stream
t, the reference amount of time, not known
D, the distance flown flying with the jet stream
d, the distance flown flying against the jet stream
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KNOWN VALUES GIVEN
w=300
D=4200
d=1400
UNKNOWNS
r, t.
ANALYZE USING DATA TABLE
________________________rate_____________time_____________Distance
WITH STREAM____________r+w_______________t________________D
AGAINST________________r-w_______________t________________d
Uniform Rates Rule for Travel gives a system of equations:
 ;
Reminder - the unknown variables are r and t. Solve either equation for t in terms of r, and substitute this into the other equation, and finish finding a formula for r. After this is done, just substitute the given values to compute r.
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