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Comment by bobbytherobot | Hacker News Reader

My follow up question if I was in that interview would be, "Is this how you operate, do you not provide critical information or am I a researcher?"

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I really don't understand all the vitriol around these types of questions. Yes, rough estimation, sense of magnitude, and ability to apply basic math to solve problems are important real life skills, and very much prerequisites in an engineering discipline. If I asked you to estimate roughly how many thumbnail images would fit in the main memory of your smartphone, would that be a better question? You should also, as an engineer, understand that the ping-pong ball question is merely a different instantiation of the exact same base abstraction.

If you can answer the question easily, humor the interviewer and move on -- because lots of people can't. I actually find it kind of fun, because then you get to see how close you get.

Also, as you become promoted, being able to work autonomously with minimal supervision and incomplete information is indeed part of your job description. If I were hiring someone, I'd want someone with a solid growth trajectory.

To be insultingly frank, from what I've seen the vitriol usually comes from people who are incapable of solving the problem because they can't think much beyond exactly what they already know, and are then upset at being rightfully passed over in favor of better candidates.

This is basically just the "how many piano tuners are there in NYC" question rephrased.

The point is that someone talks through their thought process. The solution is to say, "Well, you need to know the volume of a ping pong ball, the volume of the trailer, and the packing density of spheres. Ping pong balls are a few centimeters across, 3 maybe?, so their volume is about..."

My follow up to that follow up would be, it's 2015, internet access is ubiquitous, and if you can't find the dimensions of a standard ping pong ball and a standard semi trailer without having your hand held, then we don't need your services.

In that case, would the interviewer be fine with me pulling out my phone or laptop and looking things up during the interview? If not, then I'd strongly question the interviewer's (and, by extension, employer's) sanity.

I'd sure hope so. I'd question any interviewer's sanity if they forbade standard working tools in an interview that's supposed to gauge one's ability to work.

Note that ping-pong balls can be crushed or melted. Anyway, your reply establishes a weird power dynamic so if that's really how you do business, the candidate dodges a bullet by your forthrightness.

What's weird about expecting one's employees to be capable of looking up basic facts on their own?

It's not the expectation (irrelevant and "hoop jumping" as it is) but the rigid, adversarial tone. And like I said, there are numerous physical confounding factors that render your force-fed approach inadequate.

Expecting people to be able to look up basic information is now irrelevant and "hoop jumping"?

The adversarial tone was present in the original followup. I don't see what's wrong with continuing it. It's better than "sorry you feel that way, but we expect people to be capable of looking things up; there's the door."

This is a pretty trivial question. It should take somebody who knows Google and grade-school math about 30 seconds to solve. I'll give you ten minutes just to be generous, though.

Your "confounding factors" are irrelevant. If you crush or melt ping pong balls then what you're carrying are no longer "ping pong balls" so the question as asked can be answered by using the standard 38mm diameter of a ping pong ball and working from there.

You think those are the only confounding factors? What about tolerances so that no balls will be damaged in transit? Or is there an acceptable loss rate? How are the balls to be loaded into the trailer? Surely this is not a special ping-pong ball delivery trailer with a feeder and drainage pipe, so how will they be boxed? Do human factors affect the box size, and as a result, the number of balls that can fit? Will the trailers be stacked, and does this alter their capacity? If we don't have to box the balls, and they are stored tightly, could they settle in such a way as to become jammed, risking loss during unloading (tension is relieved, and they burst out the trailer)? Ping-pong balls are spherical, and the geometry of their fit is not as simple as that of rectangular objects, too. Are you expecting the candidate to solve a non-trivial geometry problem in a high-pressure situation? Why? Will the balls be transported between substantially different air pressures or temperatures? Is this important for ping-pong balls?

See how this could coax a poor performance out of an inquisitive, somewhat introverted candidate, rendering a false negative?

Beyond that, there's the more important adversarial tone: As an employee, will the smallest misstep result in termination? What if I have a problem that cannot be easily solved with a search engine? Is this a cooperative environment where I will feel somewhat secure as an employee, or is my status fragile? Is Mike a mercurial person who gives his employees brain-teasers with job performance implications?

Some of those are reasonable questions, like the acceptable loss rate and packaging details. Some are things you should be able to look up yourself, like the fact that spheres aren't as simple to pack as cubes. (Sphere packing is a solved problem and you can look up the efficiency pretty easily.)

My question is, if you need me to hold your hand from start to finish, then why would I pay you money just so I can do all of your work? No, I don't expect the candidate to solve a non-trivial geometry problem in a high-pressure situation. I do expect the candidate to solve a trivial Google problem in a high-pressure situation.

And, what adversarial tone? The original question was reasonable. bobbytherobot's follow-up question was completely unreasonable. Once the candidate has decided to be adversarial, my decision to continue that no longer really says anything about the work environment.

Can you not see the difference between "smallest misstep" and taking a pretty reasonable question and instantly turning it into a whine? Do you not see how it's ridiculous to ask, "or am I a researcher?" in response to that question? What position would you be interviewing for where you are not going to research some things?

Nobody gets all the info they need. You have to learn to operate by your wits. This was in a trucking/hauling company, with 1000's of people on the road responding to situations that changed constantly.

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