Question $(1)(5\mathrm{.}0$ points$)$

A flexible pavement has a $4-$inch Hot$-$mix asphalt concrete wearing surface, $8\mathrm{.}0-$inch dense$-$graded crushed stone base, and a $10$ inch crushed stone subbase. It is designed to withstand $50022-$kip single axle loads and $88036-$kip tandem axle loads per day. The subgrade CBR is $7,$ overall standard deviation is $0\mathrm{.}4,$ initial PSI is $4\mathrm{.}3$ and the final PSI is $2\mathrm{.}5.$

What is the probability that this pavement will have a PSI above $2\mathrm{.}5$ after $25$ years? $($Drainage coefficients are $1\mathrm{.}0).$ Use Both Equation $4\mathrm{.}1$ and Figure $4\mathrm{.}5$ to estimate the reliability $(R)$ and compare the results. $($Written answer please$)$