5 A particle of mass 3 kg is on a rough plane inclined at an angle of \(20 ^ { \circ }\) to the horizontal. A force of magnitude \(P \mathrm {~N}\) acting parallel to a line of greatest slope of the plane is used to keep the particle in equilibrium. The coefficient of friction between the particle and the plane is 0.35 . Show that the least possible value of \(P\) is 0.394 , correct to 3 significant figures, and find the greatest possible value of \(P\).