Question 576149
Without any wind an airplane flies at 200 miles per hour. It travels 800 miles into the wind and then returns with the wind in a total time of 8 hours and 20 minutes. Find the average speed of the wind?
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let x = speed of the wind
200+x = speed of plane with the wind
200-x = speed of plane into the wind
Travel time = Distance/speed
800/(200-x)+800/(200+x)=8-1/3=25/3
LCD:3(200-x)(200+x)
3*800(200+x)+3*800(200-x)=25(200-x)(200+x)
2400(200+x+200-x)=25(200-x)(200+x)
2400*400=25(200^2-x^2)
divide by 25
38400=40000-x^2
x^2=1600
x=40
ans:
speed of the wind=40 mph