posted by Kayla
An airplane makes a 990 km flight with a tailwind & returns, flying into the same wind. The total flying time is 3 hrs 20 mins & the airplanes speed in still air is 600 km/hr what is the the speed of the wind?
I'm as far as (990/(600-x))+(990/600+x))=10/3
but I can't figure out how to go from there!
Thanks a bunch :)
same distance, there and back
t1=3 1/3 hr -t2
10/3-990/(600+w) = 990/(600-w) so your equation is correct.
now, multipy each side by (600-w)(600+w)/990
10(600^2-w^2)/(3*990) = 600+w+600-w)
check that. Now is simplifies considerably, gather terms, and you have a quadratic equation. use the quadratic formula.
multiply by the LCD
[990 (600 + x)] + [990 (600 - x)] = 10/3 (600 - x)(600 + x)
1188000 = 10/3 (360000 - x^2) ... 356400 = 360000 - x^2
x^2 = 3600