A 12-foot ladder is leaning against a building. If the bottom of the ladder is sliding along the pavement directly away from the building at 3 feet/second, how fast is the top of the ladder moving down when the foot of the ladder is 4 feet from the wall? The top of the ladder is moving down at a rate of feet/second when the foot of the ladder is 4 feet from the wall. (Round to the nearest thousandth as needed.)