Demand at the local sports store for a new style of Tshirt has been observed to be uncertain and normally distributed with a mean of $5T-$shirts and a standard deviation of $1\mathrm{.}0$ T$-$shirts each day. A re$-$stock order placed with suppliers costs $20$ OMR, and annual holding cost per T$-$shirt is calculated at $20$ percent. The store uses an optimized continuous review policy, and purchases the T$-$shirts from suppliers for a price of $15$ OMR per unit.

The store owner is willing to accept only $2$ stockouts on average per year, and the store operates $240$ days during the year. What is the store's service level? Round your answer to $3$ decimal places.

$78\mathrm{.}9\%$

$80\%$

$99\mathrm{.}91\%$

This problem cannot be solved because the lead time is not known

$89\mathrm{.}8\%$