Brain Teasers 2

[bucknast]

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?

 

[msquared48]

Are there more rabbits in the mountains or in the summer?

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[CorBlimeyLimey]

If a man talks in a forest where there are no women around to hear him, is he still wrong?

 

[IRstuff]

If there are any women at all in that universe, then yeah...

TTFN
faq731-376

 

[IRstuff]

He was wearing the tinfoil hat and he was guessing.

actually:

http://tierneylab.blogs.nytimes.com/2009/03/16/the-puzzle-of-the-3-hats/#comment-117625

TTFN
faq731-376

 

[MintJulep]

The "solution" to the hat puzzle assumes that the first two men that don't know the color of their hats don't know based on the logical deduction process described. There is no reason to believe that they are smart enough to reason that out.

 

[msquared48]

But he was wearing the tinfoil hat to protect himself from the EMP!

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[btrueblood]

Mike, are you saying the mind control waves come from that pile of junk downtown?

 

[EQguys]

I was asked this tricky math problem.

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.

 

[TomDOT]

It's a poorly worded question "trick" for a variety of reasons:

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.

 

[TenPenny]

TomDOT

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.

 

[MintJulep]

Of course if that ladder is from the main deck to the superstructure then all 12 rungs are above water regardless of tide, freeboard, draft, weight....

 

[urgross]

A question I heard in a movie:

If you have three apples in one bag, and two apples in another bag, how many bags do you have?

 

[Maui]

jmcoope3, the man in the front is wearing a red hat.

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

http://www.EngineeringMetallurgy.com

 

[urgross]

If the man in front was wearing a blue hat, the guy in the middle would know his hat is red. If the man in front was wearing a red hat, the guy in the middle would not know if he is wearing a red hat or blue hat. Since the guy in the middle did not know the color of his own hat, the front guy has on a red hat. Both could be wearing red hats.

 

[MintJulep]

So where has our OP gotten to?

How was the interview and what question was asked?

 

[DRWeig]

Situation: your coffee is hot and your cream is chilled but you haven't mixed them yet. You won't be taking your first sip for 30 minutes, and you would like your drink to be as hot as possible when you begin enjoying it. Should you mix the coffee with the cream right now, or wait until you're ready to drink it?

Best to you,

Goober Dave

Haven't see the forum policies? Do so now: Forum Policies

 

[saf12]

coffee...
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

 

[IRstuff]

Not guessing, logic. In each of the 7 possibilities, one person can figure out, the last guy should get it 4 of the 7 possibilities, the middle guy 2 of the 7, and the first guy only 1 of 7, which is the case where he sees both of the blue hats. When the first guy sees any other possibility, he cannot determine his own color. In the cases where the middle guy sees a blue hat, he knows his is red, which occurs twice. The remaining 4 possibilities always occur with the last guy, who can't see any hats, wearing red. It's kind of an interesting problem.

TTFN
faq731-376

 

[patprimmer]

The ship is easy if we make one presumption.

The ship is floating in similar water and has not changed weight.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

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[SomptingGuy]

I was actually asked how a Newton's cradle worked once.


- Steve