Question

The pilot of a Boeing 747 is instructed to climb from 8000 ft to a cruising altitude of 29,000 ft. If the plane ascends at a rate of
3500 ft/min, how long will it take to reach the cruising altitude?​

Answer 1

Answer: 6 minutes

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Explanation:

The plane needs to go up 29,000-8,000 = 21,000 feet

It does so at a rate of 3500 ft per min

So it needs 21000/3500 = 6 minutes to get to the proper height.

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You can think of it like the equation

3500x = 21000

where x is the number of minutes needed. Dividing both sides by 3500 solves to x = 6.

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Or you could think of it like this

1 minute = 3500 feet

1/3500 minute = 1 foot (divide both sides by 3500)

1 foot = 1/3500 minute

21000 feet = 21000/3500 minute (multiply both sides by 21000)

21000 feet = 6 minutes

This shows that to go up 21000 feet, the plane needs 6 minutes to do so.