SOLUTION: flying against the jetstream, a jet travels 5250km in 7hours. Flying with the jetstream the same jet travels 6900km in 6hrs. what is the speed of the jet in still air, and what is

Question 167243: flying against the jetstream, a jet travels 5250km in 7hours. Flying with the jetstream the same jet travels 6900km in 6hrs. what is the speed of the jet in still air, and what is the speed of the jetstream?
Found 2 solutions by Alan3354, josmiceli:
Answer by Alan3354(69443) (Show Source): You can put this solution on YOUR website!
flying against the jetstream, a jet travels 5250km in 7hours. Flying with the jetstream the same jet travels 6900km in 6hrs. what is the speed of the jet in still air, and what is the speed of the jetstream?
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"Flying against" means upwind, or with a headwind, so the ground speed is the airspeed of the plane minus the wind speed.
5250km/7 hours = 750 kph
"Flying with" means downwind, or with a tailwind, and the ground speed is the sum of the plane's speed and the wind.
6900km/6hr = 1150 kph
P = the plane's airspeed
W = wind speed
-----------
P-W = 750
P+W = 1150 Add the 2 eqns
2P = 1900
P = 950 kph
W = 200 kph
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Planes and aviation and boats (and meteorologists, except the ones on TV) do not use km per hour, they use knots. 1 knot is 1 nautical mile per hour. Not knots per hour, just knots.

Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
Let speed of jetstream = km/hr
Let the speed of the plane in still air = km/hr

(1)

(2)
There are 2 equations and 2 unknowns, so I should
be able to solve
-------------------------
(1)
(1)
(2)
(2)
Divide both sides of (1) by and
divide both sides of (2) by
(1)
(2)
Add the equations

And, substituting back into (1)
(1)
(1)

The speed of the jet in still air is 950 km/hr
The speed of the jetstream is 200 km/hr
-------------
check answer:
(1)
(1)

(2)
(2)

OK

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