Measure of Temperature to Pressure in Atmosphere

The United States Standard Atmosphere measures pressure of the atmosphere at a given altitude. The information displayed in the graph below is for the altitude and the pressure. Determine the equation of the line that best fits the data points.

Using that equation, what is the pressure at altitudes of 3 km and at 7 km?

At what altitude would you expect the pressure to be 500 mb?

Verify your results on the graph by graphing the points you have just found on the line. Explain in words what information this graph is conveying.