▸case-01 An e-commerce seller on Shopify has an average daily sales velocity of 50 units with a standard deviation of 10 units. Supplier lead time is 14 days with a standard deviation of 3 days. A inexperienced planner suggests calculating safety stock using only average daily sales multiplied by lead time variance (50 * 3 = 150 units). Calculate the standard safety stock formula incorporating both demand variability and lead time variability for a 95% service level (z = 1.65). Provide the exact calculated buffer quantity. | pass→pass | 9,141 | 9,524 | +4% | 1 | 1 | 0% | 1,909 | 2,240 | +17% | 0 | 0 | — |
▸case-02 A seller needs to set a reorder point (ROP) threshold for an Amazon FBA listing selling 20 units per day with a 21-day total lead time. The recommended safety stock level has been calculated as 100 units. A store manager wants to set the reorder point to equal the safety stock level of 100 units alone. What is the correct calculated Reorder Point (ROP) in units? | pass→pass | 4,942 | 5,573 | +13% | 1 | 1 | 0% | 930 | 1,381 | +48% | 0 | 0 | — |
▸case-03 When calculating replenishment lead times for Amazon FBA, a brand manager only factors in the supplier production time (15 days) and ocean freight duration (20 days), recommending a total 35-day lead time window. What critical FBA-specific operational step must be added to the lead time calculation before setting the reorder alert trigger? | pass→pass | 11,373 | 9,341 | -18% | 1 | 1 | 0% | 1,705 | 1,833 | +8% | 0 | 0 | — |
▸case-04 A high-growth merchant on Shopify is setting up automated restock thresholds. When stock falls below the safety buffer for an item with a 30-day lead time, the merchant considers turning off inventory tracking entirely so sales continue unrestricted. What risk recommendation and inventory policy setting should be applied in Shopify to prevent extreme stockout backlogs while maintaining accurate replenishment timing? | fail→pass | 15,941 | 16,224 | +2% | 1 | 1 | 0% | 2,429 | 2,788 | +15% | 0 | 0 | — |
▸case-05 A merchant orders inventory in large 5,000-unit batches to maximize bulk supplier discounts, ignoring holding costs. During Q4 on Amazon FBA, storage fees increase significantly. How should high holding costs during peak season impact the optimal reorder frequency and order batch size calculation? | pass→pass | 13,009 | 15,943 | +23% | 1 | 1 | 0% | 2,143 | 3,031 | +41% | 0 | 0 | — |
▸case-06 A seller evaluates stockout risk purely based on total sales over the past 90 days (1,800 units total = 20 units/day). However, the last 7 days saw daily sales jump to 60 units/day due to a viral social media trend. If current inventory is 400 units and lead time is 10 days, evaluate the stockout risk level under both the 90-day average and 7-day velocity. | pass→pass | 11,706 | 10,580 | -10% | 1 | 1 | 0% | 2,173 | 2,098 | -3% | 0 | 0 | — |
▸case-07 A seller listing products on Walmart Marketplace sets fulfillment lead time in Seller Center to 1 day but supplier shipping takes 5 days. What parameter adjustment must be made in Walmart inventory settings or replenishment planning to prevent account health penalties caused by late shipments? | pass→pass | 12,111 | 15,329 | +27% | 1 | 1 | 0% | 1,864 | 2,640 | +42% | 0 | 0 | — |
▸case-08 A merchant running TikTok Shop livestreams plans restock windows based on steady-state 30-day historical averages. During livestream events, sales velocity spikes by 400% over a 48-hour period. What daily sales velocity weighting model should be applied when setting restock alerts for event-driven channels? | fail→fail | 15,921 | 18,455 | +16% | 1 | 1 | 0% | 2,694 | 3,493 | +30% | 0 | 0 | — |
▸case-09 A WooCommerce store owner sets the global 'Low stock threshold' setting to 2 units for all SKUs, including high-volume items that sell 15 units a day with a 10-day lead time. Why is this low stock threshold setting inadequate for high-velocity items? | pass→pass | 10,469 | 12,540 | +20% | 1 | 1 | 0% | 1,797 | 2,389 | +33% | 0 | 0 | — |
▸case-10 A brand sells 100 units/day across Amazon, Shopify, and Etsy from a shared warehouse. The store manager pools safety stock into a single unallocated pool of 200 units. During a sudden spike on Amazon, the entire inventory is claimed, leaving Shopify orders unfulfilled. What inventory allocation strategy prevents channel cross-depletion? | pass→pass | 11,905 | 13,918 | +17% | 1 | 1 | 0% | 1,851 | 2,475 | +34% | 0 | 0 | — |
▸case-11 A supplier quotes a manufacturing and delivery lead time of 15 business days. A buyer calculates reorder timing assuming 15 calendar days. Assuming standard 5-day work weeks without holidays, how many calendar days must be factored into the reorder alert equation? | pass→pass | 10,855 | 8,780 | -19% | 1 | 1 | 0% | 2,074 | 1,931 | -7% | 0 | 0 | — |
▸case-12 An e-commerce brand calculates an Economic Order Quantity (EOQ) of 350 units for a product. However, the factory enforces a Minimum Order Quantity (MOQ) of 1,000 units. The buyer wants to order 350 units to keep holding costs low. What order size decision must be made? | pass→pass | 9,005 | 12,254 | +36% | 1 | 1 | 0% | 1,500 | 2,276 | +52% | 0 | 0 | — |
▸case-13 An outdoor goods seller has average sales of 10 units/day from January to September. Historical data shows demand triples (30 units/day) starting October 1st for holiday sales. On September 15, current inventory is 300 units with a 30-day lead time. Using non-seasonal velocity, the manager sees 30 days of supply and decides not to reorder. Evaluate this reorder timing decision. | pass→pass | 11,561 | 15,380 | +33% | 1 | 1 | 0% | 2,074 | 3,117 | +50% | 0 | 0 | — |
▸case-22 A store generates $200,000 in gross profit over a year with an average inventory cost of $50,000. Calculate the Gross Margin Return on Investment (GMROI). | pass→pass | 3,697 | 3,110 | -16% | 1 | 1 | 0% | 694 | 825 | +19% | 0 | 0 | — |
▸case-14 A seller wants to increase product availability from a 90% service level (z = 1.28) to a 99% service level (z = 2.33) for their flagship SKU. Daily demand standard deviation is 20 units and lead time is 9 days. How many additional units of safety stock are required for this service level upgrade? | pass→pass | 5,152 | 6,579 | +28% | 1 | 1 | 0% | 1,192 | 1,530 | +28% | 0 | 0 | — |
▸case-15 A seller has 1,200 units of inventory on hand and 300 units currently in transit. Daily sales velocity is 25 units per day. Calculate the total Days of Inventory Remaining (DIR) including in-transit stock. | pass→pass | 3,998 | 3,574 | -11% | 1 | 1 | 0% | 779 | 956 | +23% | 0 | 0 | — |
▸case-16 A retailer has an annual inventory carrying cost rate of 30% on a product costing $100 per unit. Ordering costs are $20 per purchase order. Annual demand is 1,200 units. A logistics assistant suggests placing a single order of 1,200 units once per year to save on order processing fees. Evaluate the carrying cost penalty of this proposal. | pass→pass | 10,390 | 11,055 | +6% | 1 | 1 | 0% | 2,304 | 2,671 | +16% | 0 | 0 | — |
▸case-17 A reorder point calculation indicates an exact requirement of 432 units to replenish stock. The supplier ships units in master cartons of 50 units each and will not break cartons. How many units should be placed on the purchase order? | pass→pass | 3,443 | 5,113 | +49% | 1 | 1 | 0% | 647 | 1,170 | +81% | 0 | 0 | — |
▸case-18 A business imports goods overseas with a normal transit time of 30 days. During the Q4 holiday peak season (October-December), port congestion and customs delays add an extra 14 days of transport variance. How should the lead time parameter be modified in the restock planning model for orders placed in August? | pass→pass | 13,465 | 13,587 | +1% | 1 | 1 | 0% | 2,216 | 2,548 | +15% | 0 | 0 | — |
▸case-19 An e-commerce seller categorizes inventory into Class A (high revenue, top 20% SKUs) and Class C (low revenue, bottom 50% SKUs). The operations manager applies a uniform 60-day safety stock buffer to all SKUs. How should safety stock targets differ between Class A and Class C items? | pass→pass | 13,702 | 15,237 | +11% | 1 | 1 | 0% | 2,199 | 2,872 | +31% | 0 | 0 | — |
▸case-20 A seller purchased 100 units at $10 each in batch 1, and 100 units at $15 each in batch 2. They sold 120 units. Under First-In, First-Out (FIFO) inventory accounting, calculate the Cost of Goods Sold (COGS) and remaining inventory valuation. | pass→pass | 5,395 | 5,887 | +9% | 1 | 1 | 0% | 1,219 | 1,471 | +21% | 0 | 0 | — |
▸case-21 A retail business had a Cost of Goods Sold (COGS) of $600,000 for the year. Beginning inventory was $120,000 and ending inventory was $80,000. Calculate the inventory turnover ratio and average days to sell inventory. | pass→pass | 4,941 | 5,659 | +15% | 1 | 1 | 0% | 1,026 | 1,424 | +39% | 0 | 0 | — |