A helium balloon (mass including fill gas 2.1 g) is tied to a long string (mass per unit length is 3.1*10^2 g/cm, i.e., one cm of the string has a mass of 3.1*10-2 g). It rises to a height x of 210 cm, with the remainder of the string laying on the floor. If the density of air is 1.19*10-3 g/cm^3, what is the volume of the balloon?