Chapter 1, Problem 1.93PP

BIO CALCULATING LUNG VOLUME IN HUMANS. In humans, oxygen and carbon dioxide are exchanged in the blood within many small sacs called alveoli in the lungs. Alveoli provide a large surface area for gas exchange. Recent careful measurements show that the total number of alveoli in a typical pair of lungs is about 480 × 10⁶ and that the average volume of a single alveolus is 4.2 × 10⁶ μm³. (The volume of a sphere is $V\text{ = }\frac{4}{3}\pi r^3$ and the area of a sphere is A = 4πr².)

1.93    If we assume that alveoli are spherical, what is the diameter of a typical alveolus? (a) 0.20 mm; (b) 2 mm; (c) 20 mm; (d) 200 mm.