Question 217996
a twin-engined air craft can fly 1200 miles from city a to city b in 5 hours with the wind and make the return trip in 8 hours against the wind. What is the speed of the wind? 
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A to B DATA:
distance = 1200 miles ; time = 5 hrs. ; rate = d/t = 1200/5 = 240 mph
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B to A DATA:
distance = 1200 miles ; time = 8 hrs. ; rate = d/t = 1200/8 = 150 mph
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Equations:
p + w = 240 mph
p - w = 150
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Add the two equations and solve for "p":
2p = 390
p = 195 mph (speed of the plane in still air)
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Substitute into p+w=240 to solve for "w";
195 + w = 240
w = 45 mph (speed of the wind)
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Cheers,
Stan H.