Amazon Interview Question: Math Problem: You have an ups... | Glassdoor

Interview Question

Area Manager Interview Hazleton, PA

Math Problem: You have an upstream Picking department that

  feeds two downstream packing departments: A and B. 75% of your Pick volume goes to department A, which has a packing rate of 150 unites per labor hour (uph). 25% of the Pick volume goes to department B, which is for large items, and has a pack rate of 25 units per labor hour. Your pickers pick both large and small items throughout the day at an overall average rate of 100 units per labor hour. You have 25 people today for all 3 departments, and you absolutely must pack 7,500 units in department A to meet a customer promise metric. How do you allocate labor to balance the flow in your department if you work a 10 hour shift? Do not assume breaks or lunches in your answer. Department % of volume Rate (uph) People Daily Volume Pick 100% 100 ?? ?? Pack A 75% 150 ?? 7,500 Pack B 25% 25 ?? ??

Interview Answer

5 Answers


Department % of volume Rate (uph) People Daily Volume
Pick 100% 100 10 10,000
Pack A 75% 150 5 7,500
Pack B 25% 25 10 2,500

Interview Candidate on Apr 15, 2010

Stream Vol % Units/Hr Total Volume Hrs Reqd Staff Reqd
Pick 100% 100 10000 100 10
Pack A 75% 150 7500 50 5
Pack B 25% 25 2500 100 10

Anand on Apr 22, 2013

7500 units to be picked.
7500 / 150 units = 50 labor hours.
However. only 75% of the picks are sent to Dept A, so you need to increase the labor hours to account...
Thus, 67 labor hours are needed to achieve 7500 units minimum.
Each person works 10 hours...7 people minimum needed to meet the customer metric promise.

Scott on Apr 18, 2017

Avg Rate of the picker - 100 units/labor hr
Max rate of A that can be achieved - 0.75*100 = 75 units/labor hr.
Max rate of B that can be achieved - 0.25*100 = 25 units/labor hr.

To achieve 7500 units at A, picker should pick at least 10000 units (7500/0.75).
And for this labor required is 10000/(100*10) = 10 people

At A, to achieve 7500 units, labor required is 7500/(75*10) = 10 people.

Now remaining 5 people would be on B and will pack 25*10*5 = 1250 units.
Though the units coming to B from picker is 2500 (10000*0.25), the max which can be packed at B is 1250 units. So remaining1250 units will be left unpacked.

Remember, though the packing rate at A is 150 units/labor hr, the maximum units which are coming to A from picker cannot exceed 75 units/labor hr.

Anonymous on May 19, 2017

The question is about balancing the flow

in the whole process Department A has the fastest rate of 150uph. if we just use 3 people 1 at each station we will have 8 such combinations and one is left idle. this will not be able to pack 7500 small items
We need 2 people manning upstream picking + 2 at dept B and 1 at Dept A.
Total 5 people as a group this gives us 5 such group.
this group can pick 200 units per hr. this gets distributed to 150 units to Dept A and 50 units to Dept B.
In an hour they will be able to pack 150 units in A and 50 units in B.
In 10 Hrs a group of 5 can fo 1500 in dept A and 500 in Dept B
5 groups can do 7500 in dept A: condition met
5 groups can to 2500 in dept B.

with this there are no bottle necks, no blocking no starving. the flow is smooth and uniform

Anonymous on Jul 20, 2017

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