Question

Write a function that could be used to calculate the altitude of a plane arriving at JFK

International airport which was cruising at an altitude of 30,000 before it began its descent at a rate of 3,200 feet per minute. How many minutes would it be before the plane landed. Round your answer to the nearest tenth.

Answer 1

The plane landed after 9.4 minutes.

Explanation:

Function Modeling

The initial altitude of a plane arriving at JFK International Airport is 30,000 ft.

It then began its descent at a rate of 3,200 feet per minute.

Let's call t the number of minutes since the descent started. If each minute the plane descends 3,200 feet, then after t minutes it descends 3,200t.

This must be subtracted from the initial altitude, thus the altitude H is written as:

H = 30,000 - 3,200t

When the plane landed, its altitude was H=0, thus:

0 = 30,000 - 3,200t

Adding 3,200t:

3,200t = 30,000

Dividing by 3,200:

t = 30,000/3,200

t = 9.375 minutes

Rounding to the nearest tenth:

The plane landed after 9.4 minutes.