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I answered one of those mind benders nearly immediately in an interview. I figured out the trick as they were telling it basically. They asked me if I had hea
by LanceH 4y ago
I answered one of those mind benders nearly immediately in an interview. I figured out the trick as they were telling it basically. They asked me if I had heard it before. I hadn't. A final interview with the CEO and he asked if I had heard it before and I said I hadn't. I later realized based on how they were asking if I had heard it before, they thought I was lying.
The question: You get on a ski lift going up. It's 1000m long and you move at 20m/s. Between when you get on at the bottom and you get off at the top, how many of the chairs going down do you pass?
- naet 4y agoDo you pass them all?
- metamet 4y agoIt could be sum of all the chairs -1, could be -2 if the chairs are two per row, could be that the hub where they turn around has a large radius and the spacing of the chairs is close enough of that you don't "pass" them, could be 0 if there aren't any other chairs. I suspect the answer to this is "not enough information", which, I suppose, hints at an applicants requirements gathering thought process?
- giantg2 4y agoThis seems like a stupid answer for it to be n-1, but it also seems like a stupid question. What's the answer?
- LanceH 4y agoIt's n-1. I should have put the number of chairs in the question. I wasn't really trying to quiz everyone here, just identify which mind bender it was. The "twist" on the answer is that you start below all the other chairs and finish above all the other chairs, so you must have passed them all along the way. I saw this immediately and answered "99" or whatever it was. In retrospect, I think they couldn't conceive of anyone figuring it out on the fly.
- zen_1 4y agoIs the answer that you pass all but one of the chairs going down?
- boxed 4y agoSo... the answer is "impossible to know"? There's no data on how many seats there are, their distance, or whatever. There could theoretically be literally just the seat you're sitting on in the entire system. Then the answer is zero.
- deleted 4y ago[deleted]
- mjochim 4y agoLet's neglect the horizontal distance the chair(s) travel at the bottom and at the top of the lift. Then the answer is "all of them," which holds true in your one-chair scenario. The question reminds me of "how many groves are there on a vinyl record?"
- teddyh 4y agoThat depends: https://en.wikipedia.org/wiki/The_Monty_Python_Matching_Tie_and_Handkerchief https://en.wikipedia.org/wiki/The_Monty_Python_Matching_Tie_...
- mjochim 4y agoI never knew! Thanks for sharing!
- boxed 4y agoAnd how many is "all of them"? Btw it's not all, you're sitting on one, clearly you're not gonna meet that one. If I ask you how many sugars you want in your coffee and you answer with an equation I will assume you're joking or an idiot :)
- mjochim 4y agoSince I don't drink coffee, you are unlikely to ask me that question. But if you did, I might assume you are either joking or an idiot ;). Clearly, it's a trick question (with unnecessary details to distract you from a possible solution) and the one asking probably thinks they are very clever. So now, whether you accept an equation or insist that it's impossible to solve when it's not really comes down to how you want to play that game.
- deleted 4y ago[deleted]
- dorkwood 4y agoIs the answer zero chairs, since as far as we know there is only one chair on this lift?
- shanipribadi 4y agocould also be zero if it doesn't have any chairs at all because it's either a t-bar or standing gondola type.
- deleted 4y ago[deleted]
- JyB 4y agoI assume telling you a speed and not telling you how many chairs there are is intentional?
- bobbylarrybobby 4y agoAssuming an "ideal ski lift" isn't it just all of them?
- jedberg 4y agoI hate this question because it has an implicit bias that most likely the interviewer never saw. It's biased towards people who have ridden on a ski lift, which generally means someone wealthier. If you're a poor kid who's never been skiing, you'll have a harder time conceptualizing the answer.
- lordnacho 4y agoI suppose you assume the chairs are at even distances? Imagine there's a circle with marks evenly spaced, eg roots of unity. When you rotate it halfway, the point that started at the bottom has passed (vertically) all the other points ahead of it, because at some stage each point has reached the top and started going down.
- msrenee 4y agoI assume the answer is all of them?
- LightRailTycoon 4y agoYou pass all of the chairs that are going down?
- deleted 4y ago[deleted]