The shown aluminum post is reinforced with a brass core. The assembly supports an axial compressive force P applied to the rigid cap. Knowing that the post is compressed by 0.004 mm when the load is applied, find the magnitude of the load P. The aluminum tube cross-sectional area is 4100 mm² and E = 70 GPa, while the brass core cross-sectional area is 2500 mm² and E = 105 GPa.