A given gas sample consists of a mixture of He and Ar . If the partial pressure of He is 2.75 kPa and the partial pressure of Ar is 890 Pa , what is the mole fraction of He? What is the mole fraction of Ar ?

Write the complex number \( \frac{3+2 i}{1-4 i} \) in the form \( a+b i \)

Formula for standard error of the mean: \( \sigma_{\bar{x}}=\frac{\sigma}{\sqrt{n}} \) \( Z=\frac{\hat{x}-\mu}{\sigma_{x}} \) - Population mean \( =500 \) - Population standard deviation \( =100 \) - School sample mean \( =488 \) - Sample size \( =144 \)

\( \operatorname{ros} 2 \sqrt{5} ; \sqrt{8} \) y \( 4 \sqrt{2} \) ?

d.) \( \frac{1-y}{15}=\frac{(-4)}{45}-\frac{2 y+7}{3} \)

Evaluate the expression \( \sin ^{-1}\left(\cos \left(\frac{7 \pi}{6}\right)\right) \) . Give your answer as an exact value