A person with mass m1 = 55.0 kg stands at the left end of a uniform beam with mass m2 = 91.0 kg and a length L = 2.50 m. Another person with mass m3 = 67.0 kg stands on the far right end of the beam and holds a medicine ball with mass m4 = 9.00 kg. Assume that the medicine ball is at the far right end of the beam as well. Let the origin x = 0 of the coordinate system be the left end of the original position of the beam, as shown in the figure. What is the location XCM of the center of mass of the system? XCM =