The Equation $P ( a ) = 14.7 e ^ { - 0.21 a }$

Multiple Choice

The equation $P ( a ) = 14.7 e ^ { - 0.21 a }$ , where a is the altitude above sea level measured in miles, yields the atmospheric pressure in pounds per square inch. If the atmospheric pressure at Cheyenne, Wyoming, is approximately 11.57 pounds per square inch, find that city s altitude above sea level. Express your answer to the nearest hundred feet.

A) 6,400 feet
B) 6,000 feet
C) 6,200 feet
D) 5,700 feet
E) 5,900 feet