One item a computer store sells is supplied by a vendor who handles only that item. Demand for that item recently changed, and the store manager must determine when to replenish it$.$ The manager wants a probability of at least $96$ percent of not having a stockout during lead time. The manager expects demand to average a dozen units a day and have a standard deviation of two units a day. Lead time is variable, averaging four days with a standard deviation of one day.

Use the Table to get a z value that represents the $0\mathrm{.}96$ service level. Then use the formula

ROP $=$ d$*$LT $+$ z$(($LT$*\backslash$sigma $2$d$)+($d$2*\backslash$sigma $2$LT$))$

When should the manager reorder to achieve the desired probability?