# If the atmospheric pressure on Mt. Everest is one-third the atmospheric pressure at sea level, what is the partial pressure of oxygen on Everest?

So, if atmospheric pressure is 102 kPa at sea level (just to choose a convenient value), the partial pressure of the oxygen is $102 \times 0.208 = 21.22$ kPa.
On Everest, the total pressure would be 34 kPa (one-third of 102 kPa), and the partial pressure of the oxygen is $34 \times 0.208 = 7.07$ kPa.