Posted by Anonymous on Wednesday, April 13, 2011 at 12:08pm.
If the temperature is constant, then the atmospheric pressure P (in pounds/square inch) varies with the altitude above sea level h in accordance with the law given below where p0 is the atmospheric pressure at sea level and k is a constant.
P = p0ekh
If the atmospheric pressure is 14.9 lb/in2 at sea level and 12.6 lb/in2 at 4000 ft, find the atmospheric pressure at an altitude of 13,000 ft. (Round your answer to two decimal places.)
For this question I got 8.65 as my answer but for some reason I keep getting it wrong. Can someone please explain what I'm doing wrong.

Math IN URGENT NEED OF FEEDBACK  bobpursley, Wednesday, April 13, 2011 at 12:26pm
12.6=14.9k4000
k=2.3/4000
p=14.9(2.3/4000)*13000
p=7.43PSI recheck your calcs. 
Math IN URGENT NEED OF FEEDBACK  Anonymous, Wednesday, April 13, 2011 at 1:20pm
You forgot e in the calculations. I put in your number, it's not right. I'm sorry to be such a pain but I can't figure this out.

Math IN URGENT NEED OF FEEDBACK  bobpursley, Wednesday, April 13, 2011 at 1:52pm
p=14.9* e^(kh)
12.6=14.9 * e^(k4000) take ln of each side
ln(12.6)= ln(14.9)k4000
.168=k*4000
k=4.19E5
p=14.9 e^(4.19E5*13000)=14.9 e^(.5447)
p=8.65 PSI 
Math IN URGENT NEED OF FEEDBACK  Anonymous, Wednesday, April 13, 2011 at 2:09pm
Yeah, that's what I got too, but I keep getting the problem wrong. Don't worry about it though, I'm going to contact my professor and ask her what's going on. Thanks

Math IN URGENT NEED OF FEEDBACK  charles, Monday, August 5, 2013 at 6:59pm
The atmospheric pressure P in pounds per square inch (psi) is given by
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 11.39 psi, what is its altitude? (Recall that 1 mi = 5,280 ft. Round your answer to the nearest foot.)
Incorrect: Your answer is incorrect. ft