With a ground speed of 300 knots, how long will it take to descend from 21,000 feet to 11,000 feet at a rate of 2,000 feet per minute?

To determine how long it will take to descend from 21,000 feet to 11,000 feet, first calculate the total altitude change. This is done by subtracting the final altitude from the initial altitude:

21,000 feet - 11,000 feet = 10,000 feet.

Next, with a descent rate of 2,000 feet per minute, you can find the time to descend this distance by dividing the total altitude change by the rate of descent:

10,000 feet ÷ 2,000 feet per minute = 5 minutes.

This calculation shows that at a descent rate of 2,000 feet per minute, the aircraft will take 5 minutes to make the descent from 21,000 feet to 11,000 feet. Hence, the time it will take to complete the descent correctly points to the answer provided.