Probability BrainTeasers - thread

Hey guys,

I'm interviewing for some special sits funds, and they told me some MDs like to ask some probability brainteasers to the candidates. 

I'm trying to have a look at the most classical brainteasers, but would love to make a list of questions you have been asked during your interviews. this could be a good thread where we could put together the most asked/difficult brainteasers.

Thanks1

10 Comments
 

What would the solution to your first question be? You can't use Kelly formula as you don't know the actual probabilities of winning.

I would suggest setting probability of winning as p therefore EV = 1.5(p)+(-1)(1-p) = 2.5p -1 (not sure how to use this info though). Now I would size the initial bet as 1/3 of total as (1-100/150 =1/3). and then do this a few times to get a value for the actual probability of a win and use the kelly formula

Is this right? Please explain where I've gone wrong if not, 

 

In an interview setting, are you expected to calculate the actual probabilities for the second question?

Or is the series p = 1 - (364/365)(363/365)... (365-75/365) enough?

 

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