Use the following figure to help solve this problem. A spirometer with a volume of 1.3 L is filled with a mixture of oxygen and helium, with the helium concentration being 4.1 g/L. Helium does not move from the lungs into the blood or from the blood into the lungs. A subject is told to blow out all the air he possibly can. Once he finishes that exhalation, his lung volume is V2. He then puts the spirometer tube in his mouth and breathes quietly for several breaths. At the end of that time, the helium is evenly dispersed in the spirometer and the subject's lungs. A measurement shows the new concentration of helium is 1.3 g/L. What was the subject's lung volume at the start of the experiment? Must show work.