Answer:
1260 Nm
Step-by-step explanation:
As one end of the lever makes contact at the point right below the dumpster center of mass and has a distance of 0.3 m to the lever pivot point, plus the fact that the level is also approximately horizontal, we can safely assume that the dumpster gravity is directly perpendicular to the level.
This would make the torque caused by the dumpster gravity on the level is
T = LF = 4200*0.3 = 1260 Nm