As the c.m. of three particles is at (2,2,2) ∴The total mass = 1+2+3 = 6kg Now consider the 4kg mass at the position (x,y,z) Now centre of mass of total system at (0,0,0) ∴ 624 0 10 × + x = ⇒ 12 = -4x ⇒ x = -3 Similarly 624 0 12 × + y = ⇒ y = -3 624 0 12 × + z = ⇒ z = -3 From the above we can conclude that x = -3, y = -3, z = -3