Molarity = moles of solute/volume of solution in liters.
Our solution will have a volume of 72.7 mL, or 0.0727 L, since the addition of soluble LiCl will not appreciably affect the volume of the solvent.
Our solute is the LiCl, of which we have 3.75 moles.
Thus, the molarity of our LiCl solution will be (3.75 moles LiCl)/(0.0727 L) = 51.5 M LiCl.