Answer:
25%
Step-by-step explanation:
The reorder point is the inventory management system in which a certain level of inventory is set as a trigger for reordering the stock. The probability to stocking out before the new order of envelopes arises is 25%. The lead time is normally distributed with mean of 10 boxes.
(reorder point - normally distributed mean) / standard deviation
15 boxes - 10 boxes / 3 boxes = 1.67
To calculate probability of stocking out for the company,
1.67 * 15 boxes reorder point = 25%