Solve the problem.
The formula P = 14.7e-0.21x gives the average atmospheric pressure, P, in pounds per square inch, at an altitude x, in miles above sea level. Find the average atmospheric pressure for an altitude of 2.3 miles. Round your answer to the nearest tenth.
A) 9.1 lb/in.²
B) 8.4 lb/in.²
C) 11.0 lb/in.²
D) 7.8 lb/in.²