Problem $8$: Atmospheric pressure atop Mt$.$ Everest is $3\mathrm{.}30{10}^4\frac{N}{m^2}.($a$)$ What is the partial pressure of oxygen there if it is $20\mathrm{.}9\%$ of the air? $(2\mathrm{.}5$pt$)$

$($b$)$ What percent oxygen should a mountain climber breathe so that its partial pressure is the same as at sea level, where atmospheric pressure is $1\mathrm{.}01{10}^5\frac{N}{m^2}?(2\mathrm{.}5$pt$)$

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