Pressure at the top of Mount Everest is more than at the sea level
The air density at Mount Everest is less than that at the sea level. It is found by mountaineers that for one trip lasting a few hours, the extra oxygen needed by them corresponds to 30,000 cc at sea level (pressure 1 atmosphere, temperature 27∘. Assuming that the temperature around Mount Everest is −73∘C and that the oxygen cylinder has capacity of 5.2 litre, the pressure at which O2 be filled (at site) in cylinder is