Please help me with these question. Especially the last one

Annual demand for a particular LED bulb is 20000 at a lamp manufacturer that operates 250 days per year. The supplier is located in a bordering region and consequently the lead time is 2 working days. Each order to the supplier is for an EOQ of 180 units. a) Assuming constant demand during lead time, what is the reorder point? Report as a whole number with no commas. b) The usage of the LED bulbs is not constant and the demand during lead time is not constant. Assuming that demand during lead time follows a normal distribution with a mean of 160 and a standard deviation of 72. What is the required reorder point for a service level of 90%, (i.e. 0.90)? Report the answer by rounding to a whole number. (C) Assuming now that demand during lead time for LED bulbs has the following empirical distribution. For a reorder point of 232 what is the safety stock? Lead Time Demand Distribution DEMAND 52 88 124 160 196 232 268 0.1 0.15 0.15 0.2 0.15 0.15 0.1 Probability (d) Referring to the empirical lead time demand distribution in part (C), when a safety stock of 72 is used what is the probability of a stockout? Report as a two decimal digit number