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Probability aptitude questions?

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cardguy
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Joined: Nov 2012

Probability aptitude questions?
Hey everyone,
Just got this email from a close friend of mine. Just wanted to see if I could take advantage of the combined brain power here on the forum to help him out. Cheers!
Quote:Hi guys,
I have an interview coming up which will ask me a lot of statistical/probability aptitude questions.
However, unfortunately the ones I could find on the internet are not difficult enough to help me properly prepare. I know there are documents out there which have loads of these to enable people to practice for such interviews. And, i was hoping that someone in my highly skilled circle of friends would have such a document, or could tell me where I could get it.
The questions will all be probability questions designed to see how clever someone is, and are of the type:
"If there is a 50% probability of stars in one night, what is the probability of stars in either of two nights?"
I would greatly appreciate your help on this if you have access to such a document. If not, I hope all is going well with you.
Cardguy


06062013 05:31 AM 


Soma
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RE: Probability aptitude questions?
I can't have sex with your personality, and I can't put my penis in your college degree, and I can't shove my fist in your childhood dreams, so why are you sharing all this information with me?


06062013 12:32 PM 


SpiderKing
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RE: Probability aptitude questions?
"The whole point of being alpha, is doing what the fuck you want.
That's why you see real life alphas without chicks. He's doing him.
Real alphas don't tend to have game. They don't tend to care about the emotional lives of the people around them."
WIA


06062013 01:23 PM 


cardguy
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RE: Probability aptitude questions?


06062013 02:08 PM 


Divorco
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RE: Probability aptitude questions?


06062013 02:18 PM 

The following 1 user Likes Divorco's post:1 user Likes Divorco's post
cardguy

Soma
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Joined: Feb 2011
Reputation: 56

RE: Probability aptitude questions?
I can't have sex with your personality, and I can't put my penis in your college degree, and I can't shove my fist in your childhood dreams, so why are you sharing all this information with me?


06062013 03:11 PM 


LeBeau
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RE: Probability aptitude questions?
(06062013 11:16 AM)lurker Wrote: Whenever you're asked to find the probability of something occurring at least once through a set of events with defined probability, the easiest way to do it is to calculate the probability that it never happens and subtract that from 1.
The probability it never happens is the product of all the individual probability events that it doesn't occur. Here, there's a 50% chance any one night is starry, which means there's a 50% chance any one night is not starry. Thus, the probability that both nights are not starry is 0.5 * 0.5 = 0.25. This means the probability that at least one night is starry is 10.25 = 0.75.
Likewise, the probability of at least one night in three being starry would be 1 (0.5*0.5*0.5) = 10.125 = 0.875.
If he needs to know the probability of exactly X number of nights being starry out of N total, he needs to use the binomial distribution.
This. The other guiding rule here is that for 2 INDEPENDENT events, in order to get the probability that they both happen, you multiply the probabilities together.
Not to confuse the issue, but where this often breaks down is in the real world where it's much harder to measure the degree of dependence (i.e. wind currents on cloud cover, condensation, light pollution, etc.)
Which also spills into an oversimplified understanding of risks and probability in society (see the writings of Benoit Mandelbrot and Nassim Taleb).


06072013 12:46 AM 


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