###### Example A.29

From the graph of atmospheric pressure, estimate the following:

The atmospheric pressure measured at an altitude of \(15,000\) feet

The altitude at which the pressure is \(12\) inches of mercury

The point with first coordinate \(15,000\) on the graph at right has second coordinate approximately \(17.4\text{.}\) We estimate the pressure at \(15,000\) feet to be \(17.4\) inches of mercury.

The point on the graph with second coordinate \(12\) has first coordinate approximately \(25,000\text{,}\) so an atmospheric pressure of \(12\) inches of mercury occurs at about \(25,000\) feet.