Estimation question

How long will you keep the traffic light green in order to allow 100 cars to pass through? (Assume a single lane road)

Practice this question out loud. An AI interviewer asks it, follows up like a real interviewer would, and scores your answer. Type or speak.

What this question tests

Clean estimation skills applied to a physical throughput problem with clearly stated assumptions.

Clarify: single lane, so cars pass one after another, not in parallel.
Assume a car needs roughly 2 seconds of green time to start moving and clear the intersection from a stop, including reaction lag for the first car.
Assume each following car takes about 2 seconds to clear once moving in a queue.
Calculate: 100 cars times 2 seconds each equals roughly 200 seconds of green time needed.
Add a buffer for the first car's extra reaction delay, rounding to about 200 to 210 seconds total.
Sanity check: that is roughly 3.5 minutes, a long but plausible green light for clearing 100 queued cars.

States the per-car clearance assumption explicitly, about 2 seconds per car in a moving queue (assumption).
Shows the multiplication clearly: 100 times 2 seconds equals 200 seconds, then rounds sensibly.
Sanity checks the final answer against real world intuition, noting 3.5 minutes is long but plausible for 100 cars.

Forgetting that the first car needs extra reaction time before the rest of the queue can move.
Giving a number with no shown calculation.
Wildly unrealistic per-car time, like 10 seconds, without sanity checking against real traffic.

Chapters of the AI PM course that teach what this question tests.