PLEASE DO HAND COMPUTATIONS I NEED HELP LEARN FOR A THAT WE DO NOT GET COMPUTERS FOR. Thank you!

$4.$ Suppose Benetton sells $16$ different colors of a particular sweater, each of which is forecasted to have the same demand. Currently, they carry $1,000$ sweaters of safety stock for each color. The total safety stock is $16,000$ sweaters. If they were to move to a dye$-$to$-$order strategy so that stock is held in the form of undyed sweaters, how much safety stock would they need to achieve the same level of service level?Assume that demands are independent.

$5.$ Suppose there are three PetSmart stores in Rochester, MI$.$ Demand for the cat litter box averages $400$ per day per each store with a standard deviation of $200.$ They order the product from a manufacturer using the EOQ and ROP. The delivery lead time from the manufacturer is $5$ days. Assume that demands are independent.

a$.$ What is the total safety$-$stock requirement to achieve $99\mathrm{.}9\%$ service level?

b$.$ Suppose the firm considers going online. Demand for the cat litter box still averages $400$ per day per each store with a standard deviation of $200.$ The delivery lead time from the manufacturer is $5$ days. What is the total safety$-$stock requirement to achieve $99\mathrm{.}9\%$ service level?