SOLUTION: Flying against the wind, a jet travels 3780mi in 7 hours. Flying with the wind, the same jet travels 9000mi in 9 hours. What is the rate of the jet in still air and what is the rat

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Question 1063308: Flying against the wind, a jet travels 3780mi in 7 hours. Flying with the wind, the same jet travels 9000mi in 9 hours. What is the rate of the jet in still air and what is the rate of the wind?
Found 2 solutions by ikleyn, Boreal:
Answer by ikleyn(52794)   (Show Source): You can put this solution on YOUR website!
.
Flying against the wind, a jet travels 3780 mi in 7 hours. Flying with the wind, the same jet travels 9000 mi in 9 hours.
What is the rate of the jet in still air and what is the rate of the wind?
~~~~~~~~~~~~~~~~~~~~~~~~~~ 

u + v =    (speed WITH the wind)
u - v =    (speed AGAINST the wind)


OR (which is the same)

u + v = 1000,  (1)
u - v =  540.  (2)


Add the equations (1) and (2) (both sides). You will get

2u = 1540  ---->  u =  = 770 mph. It is the speed of the plane at NO WIND.

Then from (1) v = 1000 - 770 = 230 mph.  It is the speed of wind.

By the way, speed of wind of 230 mph is more than VERY STRONG hurricane condition.

But what to the person who invented this text, to it?



Answer by Boreal(15235)   (Show Source): You can put this solution on YOUR website!
s=speed in still air
w=wind speed
s+w=9000/9=1000
s-w=3780/7=540
add them
2s=1540
s=770 mph
substitute into first
w=230 mph
check in second
770-230=540
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