Can somebody help me with these questions from 11 to 13 with explanations?

o Space QUESTION 11 100% 25% 50% 75% QUESTION 12 We have a product with a mean demand of 40 and a standard dev ation of 100 How many units would we need to keepin stock to maintain a 9e% customer service lever 458 723 500 605 QUESTION 13 If an item is in stock for 10 days, then out of stock for two days, what is the item's Percent of Time in Stock? 17% @ 35% @ 83% 100% QUESTION 14