Muscles produce lactic acid when insufficient oxygen is available and is responsible for muscle cramps during vigorous exercising. It also provides the acidity found in dairy products. Chemical analysis shows that lactic acid is 39.99% carbon, 6.73% hydrogen, and 53.28% oxygen by mass. A 0.3338 g sample of lactic acid was vapourized in a sealed 300 cm³ container at 150 °C, producing a pressure of 326 torr. Determine the molecular formula of lactic acid from the data given.