Uni Interview Questions!

[Quintus Carr]

So I recently had a uni interview for engineering and got asked some (what I thought) interesting questions

1) You have a drawer of 10 blue socks and 10 red socks. Imagine you're in the dark, how many single socks do you have to take out to guarantee you have a matching pair?

2) There are three rooms:
Room A contains raging fires.
Room B contains Lions which haven't eaten for 3 years.
Room C contains murderers waiting for you.
Which room should you enter?

3) You have 6 glasses lined up, 1,2,3,4,5,6.
Glasses 1,2,3 are filled with orange juice. 4,5,6 are empty. By moving only ONE glass, how do you create a situation where the glasses are alternately filled with juice?

I'll post up some others if you like these, answers will follow

 

[dave t]

11 ?
the one with the dead lions ?
pour 2 into 5 ? nope, thats not right..3 into 5 and put it back between 1 and 2 ?

 

[Quintus Carr]

Anyone else got any ideas about number 1?

 

[Quintus Carr]

11 ?
the one with the dead lions ?
pour 2 into 5 ? nope, thats not right..3 into 5 and put it back between 1 and 2 ?

2 into 5 and replace, right the first time

 

[Tom]

No 1 = 3
No need to get out 11, because with 3 you either get all 3 the same colour, or 2 of one colour and 1 the other.

 

[Quintus Carr]

And similarly, if you wanted 2 pairs, you'd take out 5 socks

Another question:

You have a biased coin (It might favour heads say). How can you use it to make an unbiased decision by flipping it?

 

[dave t]

damn...guess I wont make a good engineer then

 

[Tom]

The default biased coin answer is to keep flipping until you get an equal number of heads/tails
Eg
1) head. - don't accept it yet
2) tail - that's 50/50 so accept heads

Or
1) head
2) head
3) tail
4) tail
50/50 again so then accept heads

My problem with the default answer is the bias has been heads, when 50/50 occurs the first to meet the equal number will be the biased side
Therefore the biased answer has been obtained in a mathematically unbiased way
But does that mean you select the alternate side - it would still mean you have a bias

What he theory does is to extrapolate and proove that at some point on a 50/50 throw of a coin what appears to be a bias can eventually be made 50/50 if you keep on going an infinite number of times
If it really is biased then heads, heads, heads, heads etc does not help you

 

[Liam92]

1) 3, as explained above
2) C - you can reason with murderers but not lions or fires xD
3) Pour glass 2's contents in to glass 5

maybe a legal career was the wrong choice for me?

 

[Canon Fodder]

2) none of the rooms, the first and third are dangerous and the lion one stinks of rotting lion corpses. Instead ring 999, report the fire and the murderers, or lock all three rooms and let the fire spread taking care of the lion corpses and the murderers and go and have a cup of tea at home instead.