Estimation question

How long would it take to empty a hot tub using only a drinking straw?

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

Quick physical estimation using flow rate reasoning, checking whether you can build a simple model instead of guessing a number.

Clarify assumptions: a standard hot tub holds roughly 1,500 liters, and a drinking straw has an inner diameter of about 5 millimeters.
Model the straw as a siphon or suction tube, since gravity draw or manual suction determines flow rate, and assume manual suction at a comfortable sustained rate.
Estimate flow rate through the straw: a person can realistically draw and expel roughly 20 to 30 milliliters per suction cycle, at about 1 cycle per second, so 20 to 30 mL per second if sustained, though real sustained rates are far lower due to fatigue.
Adjust for a more realistic sustained rate, since no person could suction constantly for hours, so assume a mechanical or automated siphon drawing at a steady 10 mL per second instead.
Compute time: 1,500 liters divided by 10 mL per second equals 150,000 seconds, roughly 41.7 hours.
State the answer as an order of magnitude, roughly 1.5 to 2 days of continuous flow, and flag that human suction alone is impractical, so a passive siphon assumption is more realistic.

Recognizes that manual human suction is not sustainable and reframes the problem as a passive siphon, a key insight many candidates miss.
States the tub volume and straw flow rate as explicit assumptions, making the chain of logic easy to follow and challenge.
Lands on an order-of-magnitude answer, around 1.5 to 2 days, framed appropriately as an estimate, not a precise figure.

Assuming a person could physically suction continuously for the full duration, ignoring fatigue and giving an unrealistic flow rate.
Skipping unit conversion between liters and milliliters, leading to an answer off by several orders of magnitude.

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