A simply supported beam (one end has a pin support and the other a roller support) is 10 ft long. The width of the beam is 3.5 in. The beam supports three concentrated loads (2.5 kips 2 ft from A to B, 1 kip 5 ft from A to B, and 2.5 kips 8 ft from A to B). The allowable bending stress in the wood is 1800 psi and the allowable shear stress is 120 psi. Determine the minimum required depth of the beam.