Estimate the Time to Drain a Home Hot Tub One Straw-Load at a Time

Suppose your only tool is a single ordinary drinking straw. Estimate how long it would take to get all the water out of a hot tub. Show how you reached the number and say how confident you are in it. ```hint Fix the method, then split the problem Decide exactly how the straw moves water before you put numbers on anything. Then break the answer into how much water the tub holds, how much one cycle with the straw moves, and how long one cycle takes. ``` ### Clarifying Questions - How may the straw be used: drawing water up by mouth and spitting it out, trapping water by covering the top with a fingertip and lifting it out, or as a siphon? - What kind of hot tub: a typical home tub for a few people, filled to its normal level, or something larger? - Is this one person working without breaks, or should the answer be in working days? - Does "empty" mean every last drop, or is a thin layer left on the seats and floor acceptable? ### What a Strong Answer Covers - An explicit choice of technique, with a reason, after weighing alternatives such as a siphon. - A clear equation: water volume divided by the water moved per cycle, multiplied by the time per cycle. - Labeled assumptions with round numbers and correct unit conversions. - Clean arithmetic, a sanity check against something intuitive, and a range that shows which input matters most. - Practical adjustments: fatigue and breaks, the last shallow layer a straw cannot reach, and water lost to evaporation over a long job. ### Follow-up Questions - If a second person joins, or you may join several straws end to end, how does the estimate change, and does a siphon become workable? - The interviewer says your answer is an order of magnitude too high. Which inputs would you recheck first, and why? - Which single assumption is your estimate most sensitive to, and how would you narrow it down?