An airplane is flying at an altitude of 40,000 feet. To avoid turbulence the pilot descends at a rate of 2,000 feet / minute for 3 minutes. He continues flying at this altitude until he decides the turbulence is over; then he ascends at a rate of 1,500 feet minute for 5.5 minutes. At what altitude is the plane now flying?

The plane is now flying at an altitude of 42,250 feet.

Step-by-step explanation:

Initially, he is at an altitude of 40,000 feet.

Descends at a rate of 2,000 feet / minute for 3 minutes.

So his altitude is now:

40,000 - 3*2,000 = 34,000

Ascends at a rate of 1,500 feet minute for 5.5 minutes.

The plane is now flying at an altitude of:

34,000 + 1,500*5.5 = 42,250

The plane is now flying at an altitude of 42,250 feet.