ATC CALCULATION: An aircraft cruising at FL300 is cleared to descend to FL100 (a 20,000 ft descent). The aircraft covers a ground distance of 60 NM during the descent at a constant groundspeed of 360 knots. What is the required Rate of Descent (ROD) in feet per minute (fpm)?

1. 1,500 fpm
2. 1,800 fpm
3. 2,000 fpm
4. 2,500 fpm