SOLUTION: An airplane took 4 hours to fly 2400 miles against a head wind. the return trip with the wind took 3 hours. What is the speed of the plane in still air and the speed oof the wind?
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Question 771159: An airplane took 4 hours to fly 2400 miles against a head wind. the return trip with the wind took 3 hours. What is the speed of the plane in still air and the speed oof the wind? Answer by mananth(16946) (Show Source):
Distance with wind 2400 miles distance against wind 2400
t=d/r against wind (x-y)
2400.00 / ( x - y )= 4.00
4.00 x - -4.00 y = 2400.00 ....................1
with wind (x+y)
2400.00 / ( x + y )= 3.00
3.00 ( x + y ) = 2400.00
3.00 x + 3.00 y = 2400.00 ...............2
Multiply (1) by 3.00
Multiply (2) by 4.00
we get
12.00 x + -12.00 y = 7200.00
12.00 x + 12.00 y = 9600.00
24.00 x = 16800.00
/ 24.00
x = 700 mph
plug value of x in (1) y
4 x -4 y = 2400
2800 -4 -2800 = 2400
-4 y = 2400
-4 y = -400 mph
y = 100
Plane 700 mph
wind 100 mph
