A flask filled with ethanol at 20.0 degree C has a total mass of 61.742 g. The flask is emptied and some ball bearings with a mass of 21.784 g are added to the flask. The flask is topped off with ethanol and now the total mass is 81.604 g. Calculate the density of the ball bearings at 20.0 degree C. The density of ethanol at this temperature is 0.78945 g/cm^3.