A solution of vinegar is 4.96% by mass acetic acid in water. Assume the density of the solution is 1g/mL. What is the pH?

I have calculated the molar mass of acetic acid to be 60.5

You had better recalculate the molar mass of acetic acid.

4.96% = 4.96g/(100 g soln) =
4.96 g/100 mL.
Convert to molarity = moles/L
Then CH3COOH ==> H^+ + CH3COO^-
Set up an ICE chart and solve for H^+, then convert to pH.