$9\mathrm{.}7$ Subbase Thickness. A flexible pavement is to be designed. The moisture factor is $1\mathrm{.}0.$ The

subgrade has been prepared to a CBR of $5.$ The structural coefficient for the $2-$incb hot mix as$-$

phalt is $0\mathrm{.}4,$ and there should be $6$ inches of asphalt base with a structural coefficient of $0\mathrm{.}3.$ The

structural coefficient of the subbase $=0\mathrm{.}10.$ The reliability is $90$ percent, standard deviation is

$0\mathrm{.}4,$ and $20,000,000$ ESAL are expected. The PSI when built was $4\mathrm{.}8$ and the PSI before rehabili$-$

tation is to be no less than $2\mathrm{.}3.$ How much subbase aggregate is required? Express your answer in

inches of subbase thickness.

$9\mathrm{.}8$ Suhbase Thickness$-$Drainage Problems. For the previous problem, if there is a high

amount of water and difficult drainage and $m$ is $0\mathrm{.}65$ for the subbase, how much subbase aggre$-$

gate is required? $($Hint: $m_1=m_2=1.)$

Please answer $9\mathrm{.}8$ and not $9\mathrm{.}7.$ The answer of $9\mathrm{.}7$ is $24$ inches of subbase aggregate is required. Thank you!