Bob and Jimmy are the elite 2-man Jamaican bobsled team. At the beginning of the race, Bob pushes the sled from behind with a force of 500 N angled 27 below horizontal. Jimmy pushes with a purely horizontal force of 400 N. The coefficient of friction between the bobsled and the ice is 0.1. Together, they cause the sled to accelerate along the level ice in a straight line at a rate of 0.84 m/s. What is the mass of the sled?