4. Hospital surgical blades The supply room of a hospital's surgical 1yard uses a twobin system to supply surgical blades, a dispensable item commonly used during surgeries. Initially nurses take any needed blades from the first bin. 'When that rst bin is emptied, a replenishment order for a new bin is immediately placed and the nurses begin taking needed blades from the second bin until the ordered bin is delivered {hopefully before the second bin runs out}. Each bin contains 10D surgical blades each, and replenishment orders take exactly two days to be delivered. (1 4.1 - It the daily demand of the surgical ward follows a normal distribution with an average of 12 blades per day and a standard deviation of 12 blades per day, what is the probability of a surgical blade stockout during a replenishment cycle? [assume demand on different days are independent] [1 4.2 What is the minimum number of blades that each bin should contain in order to keep the probability of not stocking out during any replenishment cycle above 99%