A small plane can fly 720 miles with the wind in 3 hours and can make the return trip in 4 hours. Find the speed of the plane in still air and the speed of the wind.

Question

asked Jun 8, 2019 162k views

1 Answer

Aelguindy · Answer 1 · 2019-06-12T16:09:23+0000

Answer: Speed of the plane in still air is 210 mph and Speed of the wind is 30 mph.

Explanation:

Since we have given that

A small plane can fly 720 miles with the wind in 3 hours and can make the return trip in 4 hours.

Let the speed downstream be x

Let the speed of upstream be y

So, Speed of of the plane in still air be

(x+y)/(2)

Speed of the wind be

(x-y)/(2)

According to question,

Speed of downstream is given by

$x=(720)/(3)=240\ mph$

Speed of upstream is given by

$y=(720)/(4)=180\ mph$

So, Speed of plane in still air is given by

$(x+y)/(2)=(240+180)/(2)=210\ mph$

Speed of wind is given by

$(x-y)/(2)=(240-180)/(2)=30\ mph$

Hence, Speed of the plane in still air is 210 mph and Speed of the wind is 30 mph.