[ARCHIVED THREAD] - Interview question (Page 1 of 2)
Posted: 6/2/2017 12:46:16 PM EDT
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So i started interviewing interns whose task is to write an application that visualizes the imaginary protective shield provided by lightning rods using the rolling sphere method (well known approach).
The plan is to subdivide the ground into a fine mesh, then find maximum height of buildings and equipment at the mesh points, then the user places a lightning rod anywhere and the application generates a visualization of the shield. I have a few technical questions, but one is really stumping everyone (6 so far). I think it's related to the task, and i would expect the developer to be able to answer it easily. Do you think my question is too hard for an interview? You have a plane with root point P and normal N. You have a sphere with center C and radius R. Give a simple test to determine if the plane and sphere intersect, and assuming they intersect, give the center and radius of the circle of intersection. |
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Jesus Christ man. Is that a question directly related to their day to day tasks or are you masturbating?
Eta I see now, to want them to build this app for you. I think you are seriously overestimating an intern's abilities. I've interviewed a shit-tons of college level kids and I've never run across one that could build what you are wanting in a reasonable amount of time. Including ga tech kids. |
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The first step in hiring an intern is to check out how they conduct themselves on social media. That eliminates most applicants, so the six you have interviewed would have been one or two.
Now as far as your interview question it is not hard to follow assuming they have an understanding of the field of work they are interviewing for. |
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So i started interviewing interns whose task is to write an application that visualizes the imaginary protective shield provided by lightning rods using the rolling sphere method (well known approach). The plan is to subdivide the ground into a fine mesh, then find maximum height of buildings and equipment at the mesh points, then the user places a lightning rod anywhere and the application generates a visualization of the shield. I have a few technical questions, but one is really stumping everyone (6 so far). I think it's related to the task, and i would expect the developer to be able to answer it easily. Do you think my question is too hard for an interview? You have a plane with root point P and normal N. You have a sphere with center C and radius R. Give a simple test to determine if the plane and sphere intersect, and assuming they intersect, give the center and radius of the circle of intersection. Its fine to have interview questions that are difficult and maybe even impossible to answer just to see how the candidate handles it, it happens in technical type interviews all the time. Just make sure you have a fair grading system for the candidates to make sure you are choosing the best fit. Be prepared to stick to the grading system though... choosing the 80% candidate instead of the 85% one because you had a good feeling about them can set you sailing down discrimination shit creek. As long as the question has technical merit your fine. Just stay away from "do you need Sundays off for church?" or "How many children do you plan on having?" and you'll be in good shape. |
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For that app this should be minimal knowledge You don't need to know the answer to the question to be able to code. You need to learn how to make the app use the math to return the desired result. They are separate skill sets and not interdependent in this case. |
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The first step in hiring an intern is to check out how they conduct themselves on social media. That eliminates most applicants, so the six you have interviewed would have been one or two. Now as far as your interview question it is not hard to follow assuming they have an understanding of the field of work they are interviewing for. |
 me speaking GIBBERISH!! |
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No, it's unnecessary, arbitrary and caprecious. You can write an app, exceptionally well, that will produce results using math, physics and other concepts which would otherwise be foreign to you even moments before you began working on the app. You don't need to know the answer to the question to be able to code. You need to learn how to make the app use the math to return the desired result. They are separate skill sets and not interdependent in this case. |
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No, it's unnecessary, arbitrary and caprecious. You can write an app, exceptionally well, that will produce results using math, physics and other concepts which would otherwise be foreign to you even moments before you began working on the app. You don't need to know the answer to the question to be able to code. You need to learn how to make the app use the math to return the desired result. They are separate skill sets and not interdependent in this case. Quoted:
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For that app this should be minimal knowledge You don't need to know the answer to the question to be able to code. You need to learn how to make the app use the math to return the desired result. They are separate skill sets and not interdependent in this case. I assume when OP says interns they are at least College students It's not rocket surgery |
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I don't think it is a bad question at all. All I would be looking for in an answer is the critical thinking and communication abilities. Does the applicant have an understanding of the problem and a process to solve it? Can they clearly explain it? Can they think on their feet or are they staring at me wide-eyed?
i.e. Well, we'd just need to calculate the height above the plane and then determine if the radius of the sphere is greater than or equal to that height. The X,Y coordinate for the center of the sphere will be the same for the center of the circle. The radius of the circle can be calculated with a simple ratio of the height of the sphere versus the radius, blah, blah, blah... The more I think about it, the more I like it because you can really get a feel for their personality. If they don't answer right away, but are obviously working through the process in their mind.... you have a deep thinker/analyst. Geniuses that can answer right away in detail. Bullshitters that can sell you on an answer. In your case, it sounds like you're finding people that are a few more bong hits away from the service industry. |
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This reminded me of a phone call I received from a human resources manager.
She said a friend of mine applied for a job and used me as a reference. Her only question was "Do I believe Molly would be a good employee". Vague question being vague, my response was "well that depends, if you are NASA, looking for a rocket scientist, probably not". She replied "no, we need a customer service representative". I said "oh, well that's different, she would be perfect for that job" I went on to give details on why I felt that way. She got the job. Your interview question, as presented, hurt my brain because I didn't know what kind of job this was for. I know some places ask interview questions unrelated to the job just to shake people up. I hate that crap. What kind of tree do you want to be, and why. |
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This reminded me of a phone call I received from a human resources manager. She said a friend of mine applied for a job and used me as a reference. Her only question was "Do I believe Molly would be a good employee". Vague question being vague, my response was "well that depends, if you are NASA, looking for a rocket scientist, probably not". She replied "no, we need a customer service representative". I said "oh, well that's different, she would be perfect for that job" I went on to give details on why I felt that way. She got the job. Your interview question, as presented, hurt my brain because I didn't know what kind of job this was for. I know some places ask interview questions unrelated to the job just to shake people up. I hate that crap. What kind of tree do you want to be, and why. You failed 
The very first sentence explains the job requirement 
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People at the hiring level nearly always forget at some point that the interview process is a two way decision making endeavor. I asked how many people they were interviewing for the position....over 100 at GA State U alone. Then she told me they were going to something like 7-8 other Universities. So I asked how many people hey were hiring and she said one. Wait one position as in a bunch of auditors? Nope, one single person. Interviewing hundreds of people for one position. I got up and thanked her for her time and left. She was bewildered. Homey don't play that. If you are that anal about interviewing people for your little regional CPA firm, I'd be a miserable human being working for you. |
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So i started interviewing interns whose task is to write an application that visualizes the imaginary protective shield provided by lightning rods using the rolling sphere method (well known approach). The plan is to subdivide the ground into a fine mesh, then find maximum height of buildings and equipment at the mesh points, then the user places a lightning rod anywhere and the application generates a visualization of the shield. I have a few technical questions, but one is really stumping everyone (6 so far). I think it's related to the task, and i would expect the developer to be able to answer it easily. Do you think my question is too hard for an interview? You have a plane with root point P and normal N. You have a sphere with center C and radius R. Give a simple test to determine if the plane and sphere intersect, and assuming they intersect, give the center and radius of the circle of intersection. I'm trying to understand your question. The last paragraph defines the parameters for a plane and a sphere, but where are you describing the relationship between the 2? Maybe I'm missing it and would be cut from your pool of candidates 
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It is actually a test for reading comprehension You failed
The very first sentence explains the job requirement Quoted:
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This reminded me of a phone call I received from a human resources manager. She said a friend of mine applied for a job and used me as a reference. Her only question was "Do I believe Molly would be a good employee". Vague question being vague, my response was "well that depends, if you are NASA, looking for a rocket scientist, probably not". She replied "no, we need a customer service representative". I said "oh, well that's different, she would be perfect for that job" I went on to give details on why I felt that way. She got the job. Your interview question, as presented, hurt my brain because I didn't know what kind of job this was for. I know some places ask interview questions unrelated to the job just to shake people up. I hate that crap. What kind of tree do you want to be, and why. You failed
The very first sentence explains the job requirement |
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My answer: Â 6 monthsÂ
Set up a committee to form a meeting to discuss if this should be done in house or farmed out. Schedule and have meeting Schedule a follow up meeting after researching contractors/service providers. Schedule a follow up meeting  to once again Analyze costs and feasibility : in house vs contractor Finally: Person who made the original request has left the firm, so do not act on anything - lets all just pretend that this never happened... |
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How does that apply to them getting coffee and shuffling papers around?
If you're looking for someone technically competent, why are you hiring interns? Just give them a test rooted in the fundamental basis of IQ(there are many out there which are considered non-formal IQ tests and still legal), and sort the applicants accordingly(in your head). |
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It is Jr High school level Planar Geometry I assume when OP says interns they are at least College students It's not rocket surgery Quoted:
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For that app this should be minimal knowledge You don't need to know the answer to the question to be able to code. You need to learn how to make the app use the math to return the desired result. They are separate skill sets and not interdependent in this case. I assume when OP says interns they are at least College students It's not rocket surgery |
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How does that apply to them getting coffee and shuffling papers around? If you're looking for someone technically competent, why are you hiring interns? Just give them a test rooted in the fundamental basis of IQ(there are many out there which are considered non-formal IQ tests and still legal), and sort the applicants accordingly(in your head). |
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It is Jr High school level Planar Geometry |
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An internship is supposed to be an educational opportunity for the intern as well as allowing the company to do "trail-runs" for potential future employees once they graduate. Having an intern be a secretary is a waste. Some people also just really suck at interviewing. |
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Someone once answered "Birch, because they're white" when I asked that question. Quoted:
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What kind of tree do you want to be, and why. ETA: Bonus points if they were anything other than white.
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The coffee thing was obviously a joke, but my main point about the interns is it's probably going to be a stretch to find a perfectly competent intern. Some people also just really suck at interviewing. I agree regarding interview skills. Some people are great at their job, but doing things like interviews is not their strong point. If their job will not involve stressful interviews then subjecting them to a stressful interview may not be the best way to pick the correct candidate. |
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Just wondering what is the job position and what is the applicant expected to use for the visual representation? DirectX, OpenGL, something else? I'm looking for a CS and math background, I don't expect any graphics background. I'll have them try some of the UI stuff (MFC), but it's not essential. |
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The point is this person will need to be a strong application developer first and foremost. OP already has some preconceived notion about how *he* would build one teeny tiny part of said application and is quizzing intern level candidates on what he has in his head.
What are they going to build this application with and how do you know such tools aren't already at your disposal in some framework? |
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I have no clue what the fuck you are saying. Do i get the job? Quoted:
I have no clue what the fuck you are saying. Do i get the job? You have a plane with root point P and normal N. You have a sphere with center C and radius R. Give a simple test to determine if the plane and sphere intersect, and assuming they intersect, give the center and radius of the circle of intersection. |
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So i started interviewing interns whose task is to write an application that visualizes the imaginary protective shield provided by lightning rods using the rolling sphere method (well known approach). The plan is to subdivide the ground into a fine mesh, then find maximum height of buildings and equipment at the mesh points, then the user places a lightning rod anywhere and the application generates a visualization of the shield. I have a few technical questions, but one is really stumping everyone (6 so far). I think it's related to the task, and i would expect the developer to be able to answer it easily. Do you think my question is too hard for an interview? You have a plane with root point P and normal N. You have a sphere with center C and radius R. Give a simple test to determine if the plane and sphere intersect, and assuming they intersect, give the center and radius of the circle of intersection. it took a little longer than expected but i'm finished with the interview question. can we talk about compensation and vacation days now? 
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Here's the answer:
Find distance d between plane and C by absolute value of dot(C-P, N) assuming N is unit vector. If d<R then they intersect in a circle, if d=R then the plane is tangent to sphere, and if d>R then they don't intersect. Assuming they intersect, the center of circle is the projection of C onto the plane, which is C-dot(C-P, N)*N. And the radius of the circle is sqrt(R^2-d^2). If you draw it out, which i do on a board, it should be easy. |
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agree with other answer.
first, this doesn't test anyone's ability to do anything - you're testing to see if a random person knows point projection. the answer is the center of the sphere dot product with any point on the plane. this yields the projection h (the distance of the hypotenuse or shortest distance of the sphere to the plane). if h > radius, its height is further than the sphere. if it's less, it's intersecting. knowing that dot products yield a projection for 2 points is irrelevant to almost every application. grammar! a good question should be context free. applicants should be given all necessary tools to figure out a correct answer. the reason is because nobody prepares for engineering jobs - it's their ability to solve problems and learn the context as they go. |