Question

A plane flies 435 miles with the wind and 375 miles against the wind in the same length of time. If the speed of the wind is 10 ​mph, find the speed of the plane in still air.

Answer 1

135 mph

Step-by-step explanation:

Let the speed of plane in sill water is x mph

It is given that speed of wind is 10 mph

So the speed of plane in the direction of wind speed =x+10

So the speed of plane against the direction of wind speed =x-10

It is given that plane takes same time in both with the wind speed and against the wind speed so
`(435)/(x+10)=(375)/(x-10)`

60x=8100

x=135 mph

So the speed of plane in still water is 135 mph