The 9 Oddest Tech Job Interview Questions of 2011

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Mashable has posted a list of the oddest interview questions asked by tech companies in 2011. What kind of interview questions have you been asked?

“You’re in a row boat, which is in a large tank filled with water. You have an anchor on board, which you throw overboard (the chain is long enough so the anchor rests completely on the bottom of the tank). Does the water level in the tank rise or fall?” — Asked at Tesla Motors, Mechanical Engineer candidate
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The row boat question is probably one of the more standard ME questions considering I was asked that in numerous interviews after I graduated... It may be a brain teaser for non-engineers, but it's a trivial water displacement question.

I was not asked the bouquet of flower questions during my interview with Epic... though, there were plenty of other strange questions including 5 hours of testing.
 
Forgot to add... but a variation of the row boat question is an ice cube melting in a cup of water and whether or not the water level rises.
 
Intel_Hydralisk said:
The row boat question is probably one of the more standard ME questions considering I was asked that in numerous interviews after I graduated... It may be a brain teaser for non-engineers, but it's a trivial water displacement question.
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Wouldn't it be neither? You'd be losing the downward force of gravity on the boat, which pushes down on the surface of the water, but you'd be gaining direct displacement.
 
The light bulb one is easy. They are testing for efficiency in troubleshooting I think.

You have 100 floors, 20 bulbs. You bracket.

One bulb each 10 floors. that's 10 bulbs so far. If the one on floor 80 is ok, but the one on floor 90 breaks, then you put one of each 10 remaining bulbs on floors 81-89. If it breaks on floor 87, then floor 86 is your highest floor where the bulb won't break.

The Rowboat one is interesting. Although I suspect this is wrong, I don't think the water changes. The rowboat displaces more water with the anchor on board, but then the anchor displaces water when it's tossed overboard. I think it's a wash. But this could turn into a comparison between weight displacement and object displacement, in which case I'm basically farked :)
 
canna said:
Wouldn't it be neither? You'd be losing the downward force of gravity on the boat, which pushes down on the surface of the water, but you'd be gaining direct displacement.
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volume doesn't change, weight in the same, gravity is the same if the anchor is in the boat or the water, so the displacement would be the same whether the anchor is in the boat or in the water.

As said with the ice cube one, same thing. When people say the melting ice burgs will cause a flood they wont, only ones on land that melt will add volume to the ocean.
 
When the anchor is on the boat and the entire anchor-boat system is floating, the mass of the water displaced is equal to the mass of the system (m_anchor + m_boat) so the volume of water displaced is simply (m_anchor + m_boat) / (density_water)

When the anchor is thrown overboard, the amount of water the boat displaces is calculated in the same way except with no anchor mass since the weight of the anchor does not pull on the boat due to the fact that it's on the bottom, so it's m_boat / density_water. The amount of water the anchor displaces is equal to the volume of the anchor which is equivalent to the mass of the anchor divided by the density of the anchor. So the total volume of water displaced is:
m_boat / density_water + m_anchor / density_anchor

Since the anchor sinks, density_anchor > density_water. Therefore, m_anchor / density_anchor < m_anchor / density_water. Thus since:

Water displacement with anchor on board = m_anchor / density_water + m_boat / density_water
Water displacement with anchor overboard = m_anchor / density_anchor + m_boat / density_water

Water displacement with anchor overboard must be less than water displacement with anchor on board. A lower water displacement means that the water level falls. So the water level with the anchor overboard is lower than water level with anchor on board.

I think what they want is some sort of solid reasoning / intuition more so than calculations.
 
MrGuvernment said:
volume doesn't change, weight in the same, gravity is the same if the anchor is in the boat or the water, so the displacement would be the same whether the anchor is in the boat or in the water.
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That would seemingly make sense, but the volume of water displaced is different when considering something that floats vs. something that sinks.

Namely, when an object floats, the mass of water displaced is equal to the mass of the object.

When an object sinks, the volume of water displaced is equal to the volume of the object and thus the mass of water that is displaced is less than the mass of the object since the object is more dense than water.
 
Actually, in the anchor problem, I'm pretty sure the water will rise. When the anchor is in the boat, it's displacing a volume of water which has the same mass as the anchor. Once the anchor is in the water, it's only displacing a volume of water equal to its own volume. Since an anchor is denser than water, the volume of water displaced while it's in the boat is greater than the water displaced when it's in the water. Displacement down means water level goes down.

@TechLarry - Another, faster solution is to do a binary search. Start at the 50th floor, drop a bulb. If it breaks, go down halfway (to the 25th floor) and repeat the process. You'll have an answer in 7 bulbs.
 
@ The boat thing. The boat has more area displacing the water when the anchor is inside (putting the weight in there). With the same weight but less displacement when the anchor is dropped. I would say the water level goes down.

Like putting a bowling ball in a 5 gal drum and putting that in water. Obviously the drum has more area than the ball (the sunk in part), but less weight. Take the ball out, drop it in the water. The drum will barely displace the water.

Well that's my 10 seconds of thinking about it.
 
@intel- Thanks for showing your work. I'd have wasted a good hour of searching to verify the correct answer.

@Mohonri- That was my solution too. Spent the time to figure out how many bulbs it would take.

Man, this kind kind of thing is a real productivity killer!
 
So basically we have no idea what will happen when the anchor drops? Thanks guys, I always thought you were smarter then me.

Anyone know if you have to take specific gravity into account? Or is it purely a matter of mass displacement? I've heard so many reasonable explanations, that I believe the water could do nothing, raise, and/or drop.
 
MrGuvernment said:
my head hurts now.. anyone got a tylenol?
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Some in the cupboard, I didn't take any advanced maths, or physics but to me the row boat, and anchor question would be nothing changes.

I'd say I was office 2003, easy to get along with, can do whatever is required after learning a little about the new subject, and like to get things done...unlike 2010, which is bloody awkward, you can't find what your looking for, and is clueless about older products.
 
we do know. The water level will drop.

4745454b said:
So basically we have no idea what will happen when the anchor drops? Thanks guys, I always thought you were smarter then me.
Anyone know if you have to take specific gravity into account? Or is it purely a matter of mass displacement? I've heard so many reasonable explanations, that I believe the water could do nothing, raise, and/or drop.
Click to expand...
 
4745454b said:
So basically we have no idea what will happen when the anchor drops? Thanks guys, I always thought you were smarter then me.

Anyone know if you have to take specific gravity into account? Or is it purely a matter of mass displacement? I've heard so many reasonable explanations, that I believe the water could do nothing, raise, and/or drop.
Click to expand...

It's a trick question, they left out the air speed of a laden swallow. The real answer is, which way do you want the water level to go?
 
This reminded me of an interview question my boss usually asks.

You are standing next to a flowing river and throw a red ball into the river which floats downstream. After one hour, you get into a canoe and paddle after the ball. When do you catch up to the ball?
 
The strangest question I was ever asked for a software engineer job was, "You are walking in the Sahara desert and a submarine rises out of the sand. What do you do?"
 
pseulak said:
This reminded me of an interview question my boss usually asks.

You are standing next to a flowing river and throw a red ball into the river which floats downstream. After one hour, you get into a canoe and paddle after the ball. When do you catch up to the ball?
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That's easy! The answer is, I've stopped beating my wife. :D
 
Magnus said:
That's easy! The answer is, I've stopped beating my wife. :D
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I'm pretty sure that would be an acceptable answer. At least he'd know you have the same sense of humor as the rest of the group. Well a 50/50 chance anyway. :D
 
pseulak said:
This reminded me of an interview question my boss usually asks.

You are standing next to a flowing river and throw a red ball into the river which floats downstream. After one hour, you get into a canoe and paddle after the ball. When do you catch up to the ball?
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The red ball is the job...the canoe is the door....we'll call you.
 
mcravenufo said:
The strangest question I was ever asked for a software engineer job was, "You are walking in the Sahara desert and a submarine rises out of the sand. What do you do?"
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Snap to attention and start singing 'O Canada' of course.
 
mcravenufo said:
The strangest question I was ever asked for a software engineer job was, "You are walking in the Sahara desert and a submarine rises out of the sand. What do you do?"
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Ask for a ride. It's frickin' hot out there.
 
only need one light bulb. power it in the elevator and start going up. when it breaks, well there you are.
 
I'm not even an engineer and I get these sort of questions pretty often in interviews (albeit for finance/trading).

“How many people are using Facebook in San Francisco at 2:30 p.m. on a Friday?”
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Looking for the ability to estimate rather than pull numbers out of your arse. Guess the population of SF, the percentage that use Facebook then the day/time density (you could assume averages and probably still be pretty close - well, at least not off by a factor of say 100 which is what happens when most people guess randomly).

“If Germans were the tallest people in the world, how would you prove it?”
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You can't actually prove it, you can only not disprove it. You'd assume a confidence interval (e.g. 95%) and a measure of height (e.g. average height) and then compare Germans with enough 'other people' until you are 95% certain that they are the tallest.

“Given 20 ‘destructible’ light bulbs (which break at a certain height), and a building with 100 floors, how do you determine the height that the light bulbs break?”
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Bracket like someone above said. One every 10 floors. If you want to save on bulbs you can do 1 at 50, then 75, then 87 etc and only use 8 bulbs max.

“How would you cure world hunger?”
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Most likely looking for what you presume to be the causes of hunger. As an economist I'd have to put the blame on over-regulated/protected markets (such as the EU and its common agricultural policy) and also on wars (Africa 1950-2000).
“You’re in a row boat, which is in a large tank filled with water. You have an anchor on board, which you throw overboard (the chain is long enough so the anchor rests completely on the bottom of the tank). Does the water level in the tank rise or fall?”
Click to expand...
Fall. When it is in the boat the anchor displaces its weight in water, when it's in the water it displaces its volume. Since it sinks its density is greater than that of the water therefore it will displace less causing the water to sink.

“Please spell ‘diverticulitis’.”
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If you have good pronunciation you can probably work this out.

“You have a bouquet of flowers. All but two are roses, all but two are daisies, and all but two are tulips. How many flowers do you have?”
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Three. Rose, daisy, tulip.

“How do you feel about those jokers at Congress?”
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Luring the candidate in to a false sense of security - watch what you say here.

“If you were a Microsoft Office program, which one would you be?”
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Testing whether you can deal with uncanny questions/problems. What matters isn't your answer, but that you are able to answer and give logical reasons.
 
MrGuvernment said:
volume doesn't change, weight in the same, gravity is the same if the anchor is in the boat or the water, so the displacement would be the same whether the anchor is in the boat or in the water.

As said with the ice cube one, same thing. When people say the melting ice burgs will cause a flood they wont, only ones on land that melt will add volume to the ocean.
Click to expand...

But it is not the same. The ice cube contains gasses when in a solid form. The water level will actually go down when it melts. It might take some pretty serious equipment to measure the change, but it will go down.;) It's physics. BTW the ice cube question was on my ACT test many years ago.
 
Zxcs said:
I'm not even an engineer and I get these sort of questions pretty often in interviews (albeit for finance/trading).



Looking for the ability to estimate rather than pull numbers out of your arse. Guess the population of SF, the percentage that use Facebook then the day/time density (you could assume averages and probably still be pretty close - well, at least not off by a factor of say 100 which is what happens when most people guess randomly).

You can't actually prove it, you can only not disprove it. You'd assume a confidence interval (e.g. 95%) and a measure of height (e.g. average height) and then compare Germans with enough 'other people' until you are 95% certain that they are the tallest.

Bracket like someone above said. One every 10 floors. If you want to save on bulbs you can do 1 at 50, then 75, then 87 etc and only use 8 bulbs max.


Most likely looking for what you presume to be the causes of hunger. As an economist I'd have to put the blame on over-regulated/protected markets (such as the EU and its common agricultural policy) and also on wars (Africa 1950-2000).
Fall. When it is in the boat the anchor displaces its weight in water, when it's in the water it displaces its volume. Since it sinks its density is greater than that of the water therefore it will displace less causing the water to sink.

If you have good pronunciation you can probably work this out.

Three. Rose, daisy, tulip.

Luring the candidate in to a false sense of security - watch what you say here.

Testing whether you can deal with uncanny questions/problems. What matters isn't your answer, but that you are able to answer and give logical reasons.
Click to expand...

Some questions I've been asked before:
How many gas stations are there in the US?
How many golf courses are there in Japan?
How long does it take to get to the moon at the speed of light?
I have two jars, 10 red and 10 white marbles. I can arrange the marbles however I want between the two jars. A blindfolded person will come in to the room, select one jar at random and then pull a marble out of that jar. If I want them to pull out a red marble what's the best probability I could give them?
Why do hot air balloons rise? Why does less-dense air rise?
What happens if you like a candle in the International Space Station?
How many squares on a chess board?
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TechLarry said:
The light bulb one is easy. They are testing for efficiency in troubleshooting I think.

You have 100 floors, 20 bulbs. You bracket.

One bulb each 10 floors. that's 10 bulbs so far. If the one on floor 80 is ok, but the one on floor 90 breaks, then you put one of each 10 remaining bulbs on floors 81-89. If it breaks on floor 87, then floor 86 is your highest floor where the bulb won't break.

The Rowboat one is interesting. Although I suspect this is wrong, I don't think the water changes. The rowboat displaces more water with the anchor on board, but then the anchor displaces water when it's tossed overboard. I think it's a wash. But this could turn into a comparison between weight displacement and object displacement, in which case I'm basically farked :)
Click to expand...
Actually, if you do a binary search, you'll find out the answer faster. That is, start from the 50th floor, then the 25th or 75th (depending on the result) and so on. Qualcomm should've made it a little more challenging by only giving bulbs.

As far as this question goes:
“How would you cure world hunger?” — Asked at Amazon.com, Software Developer candidate

Would it be wrong to say to kill off everyone who is hungry? :D

When I interviewed for a job back in college many years ago, it was with a financial company. They asked me how I'd devise self-driving cars. It caught me by surprise coming from a company like them, but I tried my best to describe sensors on the highways and having cars talk to each other.

For one of my colleges, I interview HS seniors and I typically ask the students an oddball question to see how they can think on their feet. :cool:
 
BallerX said:
But it is not the same. The ice cube contains gasses when in a solid form. The water level will actually go down when it melts. It might take some pretty serious equipment to measure the change, but it will go down.;) It's physics. BTW the ice cube question was on my ACT test many years ago.
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Not always...
The water level stays about the same because the density of ice is just about that of water.... or because of gasses in the ice.

You *could* make pure ice and allow no evaporation I suppose... but it's not really comparable to the question about the anchor.
 
One that my boss likes to ask is this:

"You're in a race and you'be just passed the second-place car. What place are you in now?"
 
Zangmonkey said:
One that my boss likes to ask is this:

"You're in a race and you'be just passed the second-place car. What place are you in now?"
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2nd place. Too easy!

That reminds me of a question like, "Does England have a 4th of July?" :D
 
&#8220;You have a bouquet of flowers. All but two are roses, all but two are daisies, and all but two are tulips. How many flowers do you have?&#8221;
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The answer is 3. Everyone concur?
 
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