Chemisty...Acidity of Vinegar as percent (w/v) acetic acid

A student pipetted exactly 5.0ml of vinegar into a 250ml erlenmeyer flask and added about 45ml of boiled distilled water and a drop of phenolphthalein indicator. A 50ml buret was rinsed and filled with a 0.1022M NaOH solution. The initial volume of the buret was read and recorded as 11.28ml. The NaOH solution was carefully added to the vinegar until a permanent very slight pink coloration was noticed. The buret was read again and recorded as 45.45ml. Calculate the acidity of the vinegar as percent (w/v) acetic acid