A shop owner uses a reorder point approach to restocking a certain raw material. Lead time is

$10$ days. Usage of the material is normally distributed with a mean of $80$ pounds per day and a

daily standard deviation of $8$ pounds. When should the raw material be reordered if the

acceptable risk of a stockout is $2\%($Customer service level is $98\%)?($Hint: You need to

calculate the standard deviation during the lead time$)$