The ratio of residual volume to functional residual capacity in a healthy human is about

Functional residual capacity = expiratory reserve volume + residual volume = 1,000-1,100 + 1,100-1,200 = 2,100 to 2,300 mL ≈ 2,200 mL Residual volume : expiratory reserve volume ≈ 1,100 mL : 2,200 mL = 1:2