SOLUTION: a cargo plane flies 8500 km to deliver supplies to a remote jungle camp. after dropping off the supplies the plane returns home. the speed is 150km/h faster on the return trip, cu

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Question 583416: a cargo plane flies 8500 km to deliver supplies to a remote jungle camp. after dropping off the supplies the plane returns home. the speed is 150km/h faster on the return trip, cutting the flight time by two hours. how long was the trip to the jungle
Answer by mananth(16949) About Me  (Show Source):
You can put this solution on YOUR website!
forward speed = x kph
return speed = x+150 kph
distance = 8500 km
return time less by 2 hours
time forward - time return = 2
t=d/r
8500/x-8500/(x+150)= 2
LCD = x(x+150)
multiply by LCD
8500(x+150) -8500x = 2x(x+150)
8500x+1275000-8500x=2x^2+300x
2x^2+300x-1275000=0
/2
x^2+150x-637500=0
Find the roots of the equation by quadratic formula

a= 1 , b= 150 , c= -637500

b^2-4ac= 22500 + 2550000
b^2-4ac= 2572500
%09sqrt%28%092572500%09%29=%091603.9%09
x=%28-b%2B-sqrt%28b%5E2-4ac%29%29%2F%282a%29
x1=%28-b%2Bsqrt%28b%5E2-4ac%29%29%2F%282a%29
x1=( -150 + 1603.9 )/ 2
x1= 726.95
x2=( -150 -1603.9 ) / 2
x2= -876.95
Ignore negative value
Plane speed 726.95 mph
time to camp = 8500/727= 11.69 hours
return time was 8500/877= 9.69 hours