Question

the atmospheric pressure decreases by 11% for every 1km of height above the Earth's surface from a pressure of 1005 hPa at sea level

Answer 1

y=1005×0,89^x
x stands for the Number of kilometers
It's an exponential function because it's 11 !!%!! You Always start with the value at x=0(Here 1005) and multiply it by the percentage with which it increases/decreases.