3. (6 Pts.) As shown, a C-shaped beam is subjected to a distributed load of 5 kN/m. Based on the given table of structural shapes, select the lightest C-shape beam that will safely support the load. The beam has an allowable normal stress of sigma allow = 81 MPa and an allowable shear stress of tallow = 20 MPa.

Fig: 1

Fig: 2