3. A dock worker uses a pulley system to raise a boat onto a dock. The pulley system has a mechanical efficiency of 73 %.

3. A dock worker uses a pulley system to raise a boat onto a dock. The pulley system has a mechanical efficiency of 73 %. The boat has a weight of 950 N. The pulley system lifts the boat 5 m into the air. How many newton-metres of work does the dock worker have to exert to lift the boat?