Chapter $12,$ problem $24.$

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.

What is the proper Z value corresponds to this stockout requirement?

$1\mathrm{.}645$

$1\mathrm{.}75$

$2\mathrm{.}33$

$2\mathrm{.}46$