$(10$ pts$.)$ Text Book: Ch $1,$ Problem $1\mathrm{.}12.($Copied below$)$

The gas constant $R$ has the value $2\mathrm{.}87{10}^{3}c\frac{m^2}{s^2}.K$ for dry air, when pressure is in $mb.$ Using the ideal gas law $,$ find the density of dry air at $20C$ with a pressure of $1013mb.$ Find the density of moist air at the same pressure and temperature if the relative humidity is $65\%.$

$($FOLLOW THESE INSTRUCTIONS$)$

Please calculate the density of the moist air$($kg$/m^3$only. Also please use the pressure $950mb($instead of $1013mb)$ and temperature $25C($instead of $20C).$ You can use vapor pressure table provided in class$-$handout or Appendix $C($page $765)$ or any other means. Please use $R_d=2\mathrm{.}87x{10}^{3}mbc\frac{m^3}{g.K}$