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Trow Grandmaster Cheater
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Posted: Sat Jun 25, 2011 6:37 pm Post subject: interview question that i never managed to answer |
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I have been asked the
there's 1 heavier ball in 8 balls, all look the same, use balance twice, tell it apart
interview question before (note: link is spoiler), but I was recently asked a similar question that changes in numbers, such that it reads
there's 1 ball of different mass in 36 balls, all look the same, use balance three times, tell it apart and if it is heavier or lighter than the rest.
I was unable to answer the question even after the interview. Do you guys know the solution?
Edit: 'scale' -> 'balance' _________________
Get kidnapped often.
Last edited by Trow on Sun Jun 26, 2011 3:49 pm; edited 1 time in total |
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atom0s Moderator
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Posted: Sat Jun 25, 2011 7:10 pm Post subject: |
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I don't want to click the link and spoil it so I'll ask a few questions.
Are you allowed to personally attempt to "weigh" them yourself without the scale to see if you can tell the difference between their weight?
Is there any info given regarding the weight of them and the difference for the one that is heavier?
After you attempt to divide them on the scale, are you physically allowed to move them yourself on each side to even them out? (Goes alone with the first question.)
My guess would be split the stacks in half and put them on both sides of the scale (if its an old scale like that). Then judge based on how much the one side drops more than the other (as well as how fast) to determine how much heavier the ball is. Then move 1-2 balls to the other side, hoping at least you don't move the heavier one. _________________
- Retired. |
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Trow Grandmaster Cheater
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Posted: Sat Jun 25, 2011 7:19 pm Post subject: |
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The rules of the 36-ball question is the same as the 8-ball version, and are all common sense:
- You can only weigh using the given scale. It is given to you because you cannot personally feel the difference in mass.
- My interviewer said the mass difference was "zero point one micrograms", but I think it just means "you can't feel it with your hands".
- As touching the balls would mean getting more than 0.1µg of grease onto the balls, I don't think we are meant to treat the question physically, but just as a thought experiment that tells the interviewer how smart you are under pressure. _________________
Get kidnapped often. |
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Phox I post too much
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Posted: Sun Jun 26, 2011 10:35 am Post subject: |
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I've never been able to answer that question either.
Edit: I just clicked the link, and WAIT A FUCKING SECOND. Nobody ever told me that this was one of those kindergarten two sided "scales". I thought that this was an actual scale that you put things on and you find out how much they weigh. Which would makes this impossible with only two weighings. to Jesus fuck, that fact that nobody bothered to fucking clarify that with me is beyond fucking retarded. Yep, I'm pissed. |
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Radiation Grandmaster Cheater
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Posted: Sun Jun 26, 2011 3:47 pm Post subject: |
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Phox wrote: | I've never been able to answer that question either.
Edit: I just clicked the link, and WAIT A FUCKING SECOND. Nobody ever told me that this was one of those kindergarten two sided "scales". I thought that this was an actual scale that you put things on and you find out how much they weigh. Which would makes this impossible with only two weighings. to Jesus fuck, that fact that nobody bothered to fucking clarify that with me is beyond fucking retarded. Yep, I'm pissed. |
lol, reading the OP's post, I automatically assumed it was two-sided... But haven't managed to solve the problem...  _________________
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Trow Grandmaster Cheater
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Posted: Sun Jun 26, 2011 3:50 pm Post subject: |
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LOL Phox sorry.
Also, I can solve it by weighing 4 times. Anyone got a solution for 3? _________________
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Radiation Grandmaster Cheater
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Posted: Sun Jun 26, 2011 3:56 pm Post subject: |
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OP has a good keyword: balance
how could you have mistaken it for the other type of weighing system? _________________
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Zacky Grandmaster Cheater
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Posted: Sun Jun 26, 2011 5:12 pm Post subject: |
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What kind of interview was this? |
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Trow Grandmaster Cheater
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Posted: Sun Jun 26, 2011 9:41 pm Post subject: |
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Zacky wrote: | What kind of interview was this? |
Some software company _________________
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rajaysurry How do I cheat?
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Posted: Mon Jun 27, 2011 1:48 am Post subject: |
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This is not an invitation to recite your biography. It is an opportunity to draw out the parts of your story that best sell you for the position. So if you were born and raised in Boston and are passionate about the city, that might a good topic for conversation in an interview for a marketing position with the Boston Red Sox. But it wouldn’t necessarily be worth mentioning if you were talking about a job in international banking. If you’re fluent in three languages, have worked overseas, and have parents who hail from outside the U.S., then those facts would be good ones to highlight in the interview for the international banking job. _________________
rajay surry |
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C-Dizzle Grandmaster Cheater
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Posted: Mon Jun 27, 2011 4:53 am Post subject: |
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I would assume that you would split them in half, put them on the scales, remove the balls that rose/keep the balls that sunk. Split those in half and just repeat. |
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Trow Grandmaster Cheater
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Posted: Mon Jun 27, 2011 6:45 am Post subject: |
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Arktri wrote: | I would assume that you would split them in half, put them on the scales, remove the balls that rose/keep the balls that sunk. Split those in half and just repeat. |
Alright, you have 36 balls, you weigh and keep the heavier 18 as move #1
Then, you have 18 balls, you weigh and keep the heavier 9 as move #2
How do you plan to use your remaining #3 to find out which one ball is the odd one out? _________________
Get kidnapped often. |
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AhMunRa Grandmaster Cheater Supreme
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Posted: Mon Jun 27, 2011 8:22 am Post subject: |
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You can balance each ball twice. Not you have 2 chances to find it. _________________
<Wiccaan> Bah that was supposed to say 'not saying its dead' lol. Fixing >.> |
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Ricardo I post too much
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Posted: Fri Jul 01, 2011 1:00 pm Post subject: |
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Trow wrote: | Arktri wrote: | I would assume that you would split them in half, put them on the scales, remove the balls that rose/keep the balls that sunk. Split those in half and just repeat. |
Alright, you have 36 balls, you weigh and keep the heavier 18 as move #1
Then, you have 18 balls, you weigh and keep the heavier 9 as move #2
How do you plan to use your remaining #3 to find out which one ball is the odd one out? |
you weigh only 8 balls and pray to god that they all balance out. |
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Jorg hi I post too much
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Posted: Mon Jul 04, 2011 11:29 pm Post subject: |
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What kind of interview is this? |
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