1.A 300N weight, 5m long rigid uniform ladder is leaning against a smooth vertical wall. A 750N weight manstands on a rung 4m up along the ladder from its base as shown in fig.1. What is the minimum coefficient ofthe statical friction between the ladder and the floor required to keep the system in equilibrium? The angle is53.1° on a horizontal beam. (cos53.1° = 0.6, sin53.1°  = 0.8)
(A)0.22
(B)0.42
(C)0.46
(D)0.54
(E)1.90