91影视

When I initially taught inventory planning, the arithmetic for calculatingsafety stocks was rather straightforward.I would add a percentage or some days to the cycle stock (anticipated demand during lead time) (or more likely weeks). If the lead time was two weeks, I may carry three or four weeks.

I quickly discovered that demand for some inventory goods is more unpredictable than others and that some suppliers are less dependable than others. I'd rather have too much than too little, and I would never been in trouble for having a bit too much. So, because each item and scenario is unique, I began utilizing statistics to determine the goal inventory level: (average demand * lead time) + (one-sided Z factor * demand standard deviation).

Given,

Service level = 98% = 0.98

Order Interval = R = 14 days

Lead Time = L = 3 days

Demand = D = 5000 units/year

Standard Deviation of demand = 蟽_D= 10 units/day

(R+L) = 14 + 3 = 17 days

Number of 17 day periods in a year

$\begin{array}{rcl}\mathrm{n}& =& \frac{365}{17}\\ & =& 21.47\mathrm{cycles}\mathrm{will}\mathrm{occur}\mathrm{in}\mathrm{a}\mathrm{year}\end{array}$

$\begin{array}{rcl}{\mathrm{渭}}_{\mathrm{D}\left(\mathrm{L}+\mathrm{R}\right)}& =& \frac{\mathrm{D}}{\mathrm{n}}\\ & =& \frac{5000}{21.47}\\ & =& 232.88\mathrm{units}\end{array}$

$\begin{array}{rcl}{\mathrm{未}}_{\mathrm{D}\left(\mathrm{L}+\mathrm{R}\right)}& =& {\mathrm{未}}_{\mathrm{D}}脳21.47\\ & =& 46.34\mathrm{units}\end{array}$

From the standard normal distribution table, we can see that for a service level of 0.98 or 98%, the corresponding z value is z = 2.05

So order up to level

$\begin{array}{rcl}\mathrm{S}& =& {\mathrm{渭}}_{\mathrm{D}\left(\mathrm{L}+\mathrm{R}\right)}+{\mathrm{未}}_{\mathrm{D}\left(\mathrm{L}+\mathrm{R}\right)}\\ & =& 232.88+\left(2.05脳46.34\right)\\ & =& 327.88\mathrm{or}328\mathrm{units}\end{array}$

From the given data, the inventory policy is to order (328 - On hand inventory) units = 328 - 60 = 268 boxes