Math help!!!!?

Question

The pressure of the air in the Earth's atmosphere decreases exponentially with altitude above the surface of the earth. The pressure at the Earth's surface (sea level) is about 14.7 pounds per square inch (psi) and the pressure at 2,000 feet above sea level is approximately 13.5 psi.

Write an equation that expresses pressure in terms of the altitude. (Use information given to find "r" first)

Thanks!!!

Answer 1

P=a*e^(-r*h)
For h=0, earth level P=a= 14.7 psi
for h=2,000 feet
13.5= 14.7 e^(-2,000*r) so
ln (13.5/14.7)= -2,000*r so r= ln (13.5/14.7)/(-2,000)=4,26*10^-5
so
P =14.7 * e^(-4.26*10^-5 *h)