A Fermi estimation question with a regional twist.
Break down the problem into a bottom-up estimation: start with Tehran's population, estimate the number of residential buildings, and then windows per building. State your assumptions clearly and round numbers to make calculations easy, focusing on the logical process rather than the exact answer.
Pro tip: After arriving at an estimate, sanity-check it by considering alternative angles (e.g., top-down from total window glass production) and mention that the exact number isn't as important as the structured thinking and ability to communicate assumptions.
Define what counts as a window (e.g., residential, commercial, or all buildings) and confirm whether the estimate should include all of Tehran or just urban areas.
Use known data: Tehran has about 9 million people in the city, and roughly 15 million in the metropolitan area. Assume an average household size of 4, giving about 2.25 million households.
Assume most households live in apartment buildings. If the average building has 10 units, then there are about 225,000 residential buildings. Adjust for houses or smaller buildings if needed.
For each apartment, assume 2 windows per bedroom and 1 for living room and kitchen, so about 5 windows per unit. With 10 units per building, that's 50 windows per building. Add windows for common areas (e.g., stairwells) if significant.
Multiply 225,000 buildings by 50 windows = 11.25 million residential windows. Then estimate commercial and office buildings: perhaps 10% of total buildings, with more windows per building (e.g., 100), adding another 2.25 million. Total ~13.5 million windows.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.