The figure below shows the distribution of elevation, in miles, across the earth's surface. Positive elevation denotes land above sea level; negative elevation shows land below sea level (i.e., the ocean floor). The vertical axis of the graph gives the fraction of the earth's surface per mile of elevation; the horizontal axis gives the elevation (in miles).

(a) Most of the earth's surface is ? above below at about sea level.

(b) Approximately what fraction of the earth's surface is below sea level?
Approximately
(Enter your answer as a decimal, e.g., 0.25.)

(Figure adapted from Statistics, by Freedman, Pisani, Purves, and Adikhari (New York: Norton).)