Brain Teasers
Brain Teasers
(OP)
I've got an interview with a company tomorrow that's notorious for asking difficult brain teasers.
Do you have any such questions that you remember from any of your interview experiences?
Do you have any such questions that you remember from any of your interview experiences?





RE: Brain Teasers
They are asked to see if you have, and can articulate a logical thought process.
RE: Brain Teasers
Not trying to be rude, but there is a lot available on this site in regards to this topic if you search for it.
RE: Brain Teasers
RE: Brain Teasers
RE: Brain Teasers
A particular critical part's drawing carries a high limit for the number and volume of detectable voids.
...
What would be the maximum number and volume of undetectable voids?
"
Mike Halloran
Pembroke Pines, FL, USA
RE: Brain Teasers
If I hadn't wanted the job so much I probably would have hung up on them.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Brain Teasers
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RE: Brain Teasers
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RE: Brain Teasers
-How do you make something smaller?
-How do you define engineering?
RE: Brain Teasers
-How do you define engineering? "
Probably a great way of finding out how sarcastic I'm feeling that day, maybe not so good at finding out how I think.
I like hammers, for making things smaller, and engineering is knowing which bits you can knock off and the thing will still work.
Cheers
Greg Locock
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RE: Brain Teasers
My first reaction was with an axe, then I thought about it being steel.
Mike
Total volume of undetected voids is easy by apparent vs real SG after you account for detected voids. Number well not so easy other than the total volume vs minimum detectable size as a minimum number. I guess "who cares" would not go down well.
Regards
Pat
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RE: Brain Teasers
Shrinkage.
I saw it on Seinfeld.
RE: Brain Teasers
Mike Halloran
Pembroke Pines, FL, USA
RE: Brain Teasers
Maui
www.EngineeringMetallurgy.com
RE: Brain Teasers
RE: Brain Teasers
RE: Brain Teasers
RE: Brain Teasers
I would think minimum void size would be on the order of one atom missing from the crystal lattice. You would also need a one-atom thickness between voids, so each void needs to be surrounded on all faces by atoms. Argue that those atoms are "shared" between voids, make an assumption about crystal structure, and a ratio of atoms to voids (perhaps 3:1). Take the volume of the part and atomic spacing, calculate maximum theoretical number of voids. Max volume would be 1/4 of part volume (adjust if you don't agree with my ratio.)
RE: Brain Teasers
There are three men sitting in a row looking forward, each man can only see in-front of them and cannot see what is on their heads.
A box has three red hats in it and two blue hats, these hats are put on the men at random.
The man in the back is asked if he knows what color hat he is wearing, from observation of the men in front of him, he says no.
The man in the middle is asked if he knows what color hat he is wearing, from observation of the man in front of him, he says no.
The man in the front is asked if he knows what color hat he is wearing, from inference, he says yes.
What color hat is he wearing and how does he know?
RE: Brain Teasers
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com
RE: Brain Teasers
RE: Brain Teasers
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RE: Brain Teasers
actually:
http://tierneylab.blogs.nytimes.com/2009/03/16/the...
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RE: Brain Teasers
RE: Brain Teasers
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com
RE: Brain Teasers
RE: Brain Teasers
A ship has a ladder with 12 rungs above water during the low tide. How many rungs are above water during high tide 24 hours later, if the rate of rise of water level is 0.5inches per hour and the rungs are spaced 4 inches apart.
RE: Brain Teasers
Low tide and high tide are not 24 hours apart. They are roughly 6 hours apart, but not quite. Do you happen to know this fact? Did the writer?
So, if we presume they meant 24 hours later, 12 rungs will be above the water. If they meant the next high tide, we get 3 inches, so either 11 or 12 rungs will be above the water, depending on the (undefined) start point relative to the lowest rung.
Rate of seawater rise is nonlinear during those 6 hours.
Tide height can vary significantly from one high (or low) to the next.
...and the most likely intended answer: ships often (but not always) will float with the tide, leaving us 12 rungs anyway. (hey, if I put that first, it would give away the intended answer.)
One of the "not always" examples would be the USS Enterprise aircraft carrier (retired) in Corpus Christi, TX - it rests on the bottom and does not float with the tide.
Rare example you say? Sure, lets go with reality then:
Most likely the ship will have a change in its weight of ballast, fuel and/or cargo thus changing the depth. Precious few ships sit around in the water with no change to weight over a 24 hour period. Maybe you have a persnickety captain who always trims to within a few inches - very unlikely.
RE: Brain Teasers
We could suggest that if high tide is 24 hours after low tide, the ship must be somewhere else, so we'd have to calculate how much fuel was used to travel that far, in order to figure out the change in freeboard.
RE: Brain Teasers
RE: Brain Teasers
If you have three apples in one bag, and two apples in another bag, how many bags do you have?
RE: Brain Teasers
The man in back could only know what his hat color is if the two men in front of him were both wearing blue hats. Since he doesn't know, at least one of the men in front of him is wearing a red hat. Since the second man can't tell what hat color he has on either (it has to be either red or blue), and we know based on the first man's reply that at least one of the remaining two men is wearing a red hat, this indicates that the man in the front is wearing a red hat. Make sense?
Maui
www.EngineeringMetallurgy.com
RE: Brain Teasers
RE: Brain Teasers
How was the interview and what question was asked?
RE: Brain Teasers
Best to you,
Goober Dave
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RE: Brain Teasers
wait.
That hat thing has got me...
if person one and person two have no information. then person three is guessing.
ship...
if it's 24 hours later.. then it would not be high tide it would be low tide, the situation has not changed.
I suppose i'm under thinking all of it
RE: Brain Teasers
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RE: Brain Teasers
The ship is floating in similar water and has not changed weight.
Regards
Pat
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RE: Brain Teasers
- Steve
RE: Brain Teasers
For the hottest coffee thirty minutes from now, mix them whenever you want and nuke it in the microwave for a minute when you're ready to sip.
The thermo calculations can't be done anyway, there are too many unknowns.
I got a big smile from the interviewer. It might have been a sarcastic smile, though. I didn't get the job offer.
Best to you,
Goober Dave
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RE: Brain Teasers
RE: Brain Teasers
Best to you,
Goober Dave
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RE: Brain Teasers
If the coffee's in a heated pot, all the heat it loses will be replaced during the half hour. Wait and pour it then.
Run some tap water or hot water over the cream container in the breakroom sink. Give it some extra heat to start with.
Etc...
In other words, you're right, Compositepro, in one sense. If he were looking for an engineer who knows his or her stuff, and knows when to stop digging for data, your answer gets the job.
I would personally prefer to hire the engineer who suggests methods that would improve the outcome over the two less-than-optimal methods he was given to evaluate. I would also prefer to work for someone who expects questioning.
Best to you,
Goober Dave
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RE: Brain Teasers
I'll make (and state*) for the interviewer some environmental assumptions: We have no external heat inputs available, there are two containers (one for cream, one for coffee, and that we have significantly more coffee than cream. The coffee will be significantly above ambient temperature, the cream will be moderately below ambient temperature. These are the "best fit" of likely conditions - coffee around 190C, cream around 2C, environment around 20C.
Immediately add the cream to the coffee, then place the cream container on top of the coffee cup to arrest evaporative cooling and reduce convective cooling.
Ha!
*Throw in a question back, such as "Okay, is that the limit of the data I have on hand or can reasonably obtain?" to make sure it isn't one of those "lets see how you research" type of questions.
RE: Brain Teasers
How does one obtain 190C coffee at atmospheric pressure again?
RE: Brain Teasers
"Engineers like to solve problems. If there are no problems handily available, they will create their own problems." -Scott Adams
RE: Brain Teasers
Got to the hotel breakfast buffet, and poured a cup of coffee and a touch of hot milk.
The coffee was terrible, but I needed a second cup regardless.
This time I was behind one of the natives, and noticed he poured about 1/4 cup and the rest milk. I followed suit, and behold, a latte! The reason for the hot milk.
RE: Brain Teasers
RE: Brain Teasers
Regards
Pat
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RE: Brain Teasers
A.
RE: Brain Teasers
Regards
Pat
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RE: Brain Teasers
- Steve
RE: Brain Teasers
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Brain Teasers
Regards
Pat
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RE: Brain Teasers
Regards
Pat
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RE: Brain Teasers
I was 17, hundreds of miles from home, desperately needing to find a sponsor and quite intimidated by the panel of 3 interviewers. So I didn't argue the case. Or get the job.
- Steve
RE: Brain Teasers
I've got a PHD is Broscience
RE: Brain Teasers
RE: Brain Teasers
Unless you mean the cooling rate of the room, in which case you'd need to measure the efficacy of the insulation and the difference between the inside/outside temperature.
"Engineers like to solve problems. If there are no problems handily available, they will create their own problems." -Scott Adams
RE: Brain Teasers
Cooling rate is negative - fridge is heating up the room. Start with average power draw by the fridge, convert to heat. Then go forward with EngineerErrant's calcs.
RE: Brain Teasers
- Steve
RE: Brain Teasers
Comprehension is not understanding. Understanding is not wisdom. And it is wisdom that gives us the ability to apply what we know, to our real world situations
RE: Brain Teasers
Once the brick is removed it sinks and displaces its volume in water which is less than its weight.
If the brick is SG 1 or less it displaces its weight in water either way so no change.
Unless otherwise specified the definition of a brick is a ceramic or earthenware object used as a building material. these bricks always have an SG of more than 1.
The interviewer was less than justified in being smug, however proving that probably goes against you and reinforces "lifes not fair".
Regards
Pat
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RE: Brain Teasers
Cheers
Greg Locock
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RE: Brain Teasers
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Brain Teasers
I had an onsite caravan where I cut a hole in the wall the same size as the fridge. Put the fridge in with the condenser exposed to the outside then sealed the sides of the fridge to the wall of the van. Worked for me as we only used the van in summer.
I put some strategically placed trellis work to protect the condenser from passers by and vise versa.
Regards
Pat
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RE: Brain Teasers
1) I have a big brick of gold in the boat. The boat is close to sinking due to the huge weight of the brick and the water level in the pond is close to overflowing its banks. I throw it in. My boat is suddenly unladen, so the water level drops massively. When everything has stopped bouncing around, the level is slightly higher (volume of gold brick) than it would have been had there been no brick to start with. But lower than it was when the boat was thinking of sinking.
2) My brick is expanded polystyrene. It floats nicely on the pond. Nothing changes with the water level.
- Steve