Supply chains have become somewhat more stable since March $2020($still volatile, but better than back then$),$ so the retailer is currently in the process of

establishing a contract with a disposable mask supplier. The supplier has agreed to sell masks to the retailer for $$18$ per box and will make deliveries any time

the supplier places an order for a cost of $$100$ per delivery $($the delivery cost is independent of the size of the order$).$ The supplier's lead time is fairly stable $-$

about $3$ days.

On the demand side, estimates are much more conservative compared to the March $-$ August timeframe: demand is assumed to be normal with $=1200$

and $=60$ boxes per month. Other costs include $h=$$$2\mathrm{.}50$ per box per month and $b=$$$29$ per box per month. The number of work days each month is

$($a$)$ The retailer is considering an order policy in which the safety stock level is $SS=25$ boxes of masks. What is the corresponding reorder level? $(15$pts$)$

$($b$)$ If $SS=25,$ what would be the corresponding CSL$?(4$pts$)$

$($c$)$ Suppose the reorder level is $s=200.$ What is the corresponding order quantity? $(5$pts$)$

$($d$)$ Find a initial estimates of the optimal service level and optimal $($s$,$Q$)$ policy. $(3$pts$)$

$($e$)$ Find the optimal service level and optimal $($s$,$Q$)$ policy. $(6$pts$)$