The atmospheric pressure P in pounds per square inch (psi) is given by

Question

P = 14.7 e−0.21 a
where a is the altitude above sea level (in miles). If a city has an atmospheric pressure of 12.21 psi, what is its altitude? (Recall that 1 mi = 5,280 ft. Round your answer to the nearest foot.)

Answer 1

P(a)=12.21=14.7*e^-0.21a
Solve for a:

e^-0.21a=12.21/14.7
Take log on both sides, log(e(x))=x
-0.21a=log(12.21/14.7)
a=log(12.21/14.7)/(-0.21)
=?