I need help with a calculus homework problem??

Question

Atmospheric pressure P decrease as altitude h increases. At a temperature of 15 degrees celsius, the pressure is 101 3 kPa at sea level, 87.1 kPa at h= 1 km and 74.9 kPa at h=2 km.

It says to use a linear approximation to estimate the atmospheric pressure at an altitude of 3 km.

Any help is gretly appreciated. thanks

Answer 1

The answer should be 62.7 if your assuming a linear approximation.  From 1 km to 2km your pressure dropped 12.2, so if you go to 3km your pressure should drop another 12.2... 74.9-12.2= 62.7