Final answer:
The lung efficiency can be calculated by finding the ratio of vital capacity (VC) to total lung capacity (TLC). In this case, the lung efficiency is 87.5%.
Step-by-step explanation:
Lung efficiency can be determined by calculating the ratio of vital capacity (VC) to total lung capacity (TLC). VC is the sum of tidal volume (TV), expiratory reserve volume (ERV), and inspiratory reserve volume (IRV), while TLC is the sum of TV, ERV, IRV, and residual volume (RV). In this case, TLC is given as 6.4 L and RV as 0.8 L. So, the ratio of VC to TLC can be calculated as (TLC - RV) / TLC. Substituting the given values, the lung efficiency is (6.4 - 0.8) / 6.4 = 0.875, or 87.5%.