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## Homework Statement

A Cessna 150 averages 150 mph in still air. With a tailwind it is able to make a trip in 2 1/3 hours. Because of the headwind, it is only able to make the return trip in 3 1/2 hours. What is the average wind speed?

## Homework Equations

(1) If x = wind speed and y = still air speed

∴ resultant speed (tailwind) = x + y

∴ resultant speed (headwind) = x - y

(2) d = rt

## The Attempt at a Solution

let x = wind speed

still air speed = 150 mph

tailwind time = 2 1/3 hours

tailwind speed = 150 + x

headwind time = 3/12 hours

headwind speed = 150 - x

I used these as given for the problem, expressed distance in terms of tailwind/headwind time and rates, set distance as constant (equates), solves for x then gets 57.69 as answer.

but in the book, the answer is 30 mph. What is the problem with my solution?

Thanks in advance.