Trick questions asked on a job interview

Hi,

Let me open a new topic about trick questions on a job interview by major corporations like IBM, Intel, Microsoft ... Hopefully it will help some of us preparing for interview .

Here was a brain-twisting question I was asked during an interview with a large corporation, 5 years ago (sorry, can't tell the company name since I don't want to get into trouble with my company)

Given 5 coins with 4 coins having the same weight and 1 coin heavier than the rest , using a jeweler scale, what is the fastest way to find the heavier coin ?

Some other questions I gathered :

1) Why are manhole cover (nắp cống) round rather than square ?

2) How do they make M&M
The main issue is how the manufacturer gets a perfectly smooth , layered candy shell on a mass-produced food that NEVER knows a human touch until the bag is opened ?

3) Mike and Tim have $21 between them . Mike has $20 more than Tim. How much does each have ? You can' t use fraction

Give it some thoughts, I will come back to give you an answer (my answer anyway)

Q1. Take 1 coin out, weigh the rest. If they are of the same weight, the coin previously taken is the one we have to find. If not, compare the 2 coins of the heavier part. . Obviously this is theoretically the best way. I am not quite sure 'bout my solution, though. Maybe we can easily obtain the result using bare eyes ? The heavier must be the thicker, or bigger ?
Q2. A square manhole has 2 diagonals which are longer than its side, and so it can fall into the manhole. Round manhole covers have their "diagonal" of the same length, and cannot fall into the manhole.
Q3. What do you mean ?? . Still haven't got the point. M&M, hic.
Q4. Should be like this : Mike has $20 and a 50c coin, Tim has a 50c coin ( the poorest all over the world ). A 50c coin is not considered to be half of a $1 note, they are in different kinds.
Được bart sửa chữa / chuyển vào 11:52 ngày 09/05/2003

Bart, my hat's off to you . You'd pass the test easily with those answers . Here they are :
For the question about finding the heavier coin among the 5 coins using a jeweler's scale : 1)Pick out two coins and weight them against two other coins . If they are balanced out then the coin left is the one. If one set of 2 coins is heavier than the other set, then weight those 2 coins to get the heaviest. So, the maximum is two (2) steps . This is the concept of binary sort (Computer Science major)
2) The question about why manhole cover is always round , Bart's answer is the perfect one . Others acceptable one is that people can roll a circular cover if it needs to be moved a short distance while square cover would require a dolly or two persons, another one is the round cover need not to be rotated to fit the hole .
3)The M&M chocolate candy is the toughest one : the chocolate centers are cast in little molds then they are put in a big rotating drum , like a cement mixer . While jostling in the drum, they are sprayed with a sugary liquid that hardens into white candy shell . Constant movement prevents the candies from congealing into a big slums . They're then squirted with colored sugar liquid . This hardens into the coasting on top.
This question is meant to see whether the candidate can come up with convincing answer and avoid saying something stupid
4) The last one, again Bart was absolutely right . Candidates are tempted to answer that Mike has $20 while Tim has $1 but the difference is $19 not $20 . The right answer is $20 and 50 cents vs 50 cents since 50 cents is a whole number, not a fraction . This is to test the candidate's conviction to stand up for something that's right. Not a "yes" man type.
By the way, I never knew the right answers until I read them in Reader's Digest magazine . I did try to ask my interviewer when it was done but he refused to give me those answers. Fun huh ! For your information, candidate also has to take an IQ test with questions testing logic and mentality when working under stress . For professional hires, technical questions are also included . The good part is they can't discriminate about age, gender, race or anything else . Merit/qualification is the sole criteria . There was always aberration though.
Kudos to our winner : Bart !
Được tdhung sửa chữa / chuyển vào 06:38 ngày 11/05/2003

Hi bro,
Luckily I had the right answer. But it took me quite a long time, more than an hour. When being placed under real stresses, I am afraid that I can't do that correctly, the point is that it was nearly 12pm of Friday, and I had no class at all, so I tried to solve your questions with an open mind, and things got easier, didn't they ?
For Q2 : I love eating MM, but not producing it. Thanks for the answer, I didn't know that before. Hope that I will not get these kinds of questions when I am interviewed, in the future
Thanks for your questions, they are really interesting. Cheers !
Được bart sửa chữa / chuyển vào 15:23 ngày 11/05/2003

You're good, Bart, and don't be too humble. Just sharpen your mind and get ready to use it when opportunity knocks.
Cheers.