PE CIVIL: STRUCTURAL PRACTICE EXAM

$53.$ The pipe member shown in the figure has a constant section and the following properties:

Outside diameter $10i$N

Moment of inerti $90i{n}^4$

Area $7$in$^2$

Neglecting the weight of the pipe, the maximum compressive stress $($ksi$)$at the support is most nearly

Answer is B $4\mathrm{.}9($ by taking moment at center of pipe therefore M $=20$k$,$ stress flexture$=7\mathrm{.}8$ ksi and stress axial $=2\mathrm{.}9,$ max compressive stress is $-7\mathrm{.}8+2\mathrm{.}9=-4\mathrm{.}9.)$ how $?$