As a precaution against the problem of decompression sickness,
N2 is sometimes replaced with helium. Calculate the equilibrated
arterial plasma helium concentration that would be present in the
blood of a diver if the air mixture within his tank contains 21%
oxygen, 79% helium, 0% CO2 at atmospheric pressure (760 mm Hg),
airway PH2O = 47 mm Hg and He solubility is equal to 0.085 ml/100
ml blood x mm Hg. You can assume that alveolar PHe = arterial PHe.
(Remember to express your result in correct units)