Mock PM Interview with Product Experts
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Say, Amazon has to come up with a Fulfillment centre to serve a community in a remote location. How would you estimate number of warehouse operators required?
Start by defining what are the processes required in a fulfillment centre and what is the standard through-put rate for each of the process.
A typical Fulfilment center has following process –
Unloading (Unloading shipments from trailers to dock)
Inwarding (Doing a QA of the inwarded material and recording them on the system)
Stowing (Storing the material on the racks)
Picking (Picking products (that has been ordered) from a pick-list)
Packing (Packing the products and putting the labels)
Dispatch (Sorting the packets and moving to appropriate dispatch lots)
Ancillary processes – Security, Stock-Takes, IT/Handheld System management, Buffer in case of any leave/absence of an operator
Assumptions to be made –
FC would be maintaining stock for frequently ordered products (for which promise of delivery would be short); other than that, the product would have to be flown to the nearest airport and then transferred to the FC via trailers.
Next, estimate number of average orders coming to the fulfilment center. You can base your estimate on population the FC would be serving.
Say, you’ve estimated incoming daily orders to be 100K
And incoming load to the dock to be same ~ 100K
Next, discuss the through-put rates for each process.
Say, following are the through-puts for each process –
Unloading – 100 item / hr
Inwarding – 50 item / hr
Stowing – 80 item / hr
Picking – 80 item / hr
Packing – 40 item / hr
Dispatch – 90 item / hr
Assuming, there are 2 shifts of 8 hours each (which excludes lunch/break time).
Calculate man-hours required for each process and next estimate number of operators required.
E.g. in order to serve 100K orders ~ 50K order per shift;
Picking – 50K/80 man-hours = 625 man-hours
Packing – 50K/40 man-hours = 1250 man-hours
Dispatch – 50K/90 man-hours = 555 man-hours
Operators required –
Picking – 625 man-hours = 625 / 8 ~ 79 operators reqd.
Packing – 1250 man-hours = 1250 / 8 ~ 156 operators reqd.
Dispatch – 555 man-hours = 555 / 8 ~ 70 operators reqd.
Similarly, you can estimate number of operators required for each process in the Inbound processes. Next add up operators for ancillary functions – Security, Stock-Take + Buffer.