Blanked for a second on where to even start.
Break the problem into life stages (childhood, adolescence, adulthood, senior) and estimate shoe consumption per stage based on frequency of replacement and number of pairs owned. Use round numbers and state assumptions clearly, then sum to get a lifetime total. Finally, sanity-check the number against personal experience or known data.
Pro tip: Show your work and communicate your assumptions; Amazon values structured thinking and the ability to simplify ambiguous problems. Also, relate the estimate to potential business insights, such as market size for shoes or opportunities for Amazon in the footwear category.
Confirm what is meant by 'average person' and 'lifetime'—assume global average and lifespan of 80 years. Ask if the interviewer wants a specific region or demographic.
Divide life into stages: childhood (0-12), teen (13-19), adult (20-64), senior (65+). Estimate years in each stage and typical shoe consumption patterns.
For each stage, estimate number of pairs owned at a time and how often they are replaced. Multiply to get total pairs per stage.
Add up pairs from all stages to get lifetime total. Check if the number seems reasonable (e.g., 1-2 pairs per year on average).
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.