Dry air moves upward, it expands and in so doing cools at a rate of about $\"\"$ for $\"\"$ rise, up to about $\"\"$ . \ \ \ \ The ground temp is $\"\"$ .

(a)

Find a formula for the temp at height .

Let $\"\"$ is a height in meters.

$\"\"$ is a temperature.

$\"\"$

At ground level $\"\"$ it is at $\"\"$ .

Hence, $\"\"$ it goes down $\"\"$ for every $\"\"$ .

At $\"\"$ , it would be $\"\"$ extra.

(b)

Find a plane takes off and reached a maximum height of $\"\"$ .

Here,

$\"\"$

A plane takes off and reached a maximum height of $\"\"$ is

$\"\"$

A plane takes off and reached a maximum height of $\"\"$ is

$\"\"$

The interval notation is $\"\"$ .