Does anybody know of a good book or two that I can use to brush up on probability theory, multiplying/dividing large numbers mentally, and anything else that might be useful?
I got grilled like crazy last night on probability and some mental math problems. Do they honestly expect you to do everything in your head on the spot, or are they more concerned with you thinking out loud and trying to figure out the problem?
They are more concerned with your logic than the actual answer. Don't allow your answer to be too inaccurate, b/c that could way you down as well. Hope this helps
When I interviewed just a couple months ago, it was much the same - tough brain teasers, mental math, and straight up probability questions. I think if you read all the available info, you can do very well on the brain teasers - "heard on the street", as someone mentioned earlier is a good book, and a few other ones as well - just go on amazon and do a related search. Anyway, they mostly want you to, if not get the right answer, attempt to solve the problem thinking in the right direction. For the mental math and probability questions - you should get these right 100% (almost) just study up on conditional probability (i.e. Bayes Theorem).
Example: "Tell me the hardest thing you have ever done in your life." Me: "Well, I ... Them: "WHAT IS 21 TIMES 39?" Example: Degree difference between the hour hand and minute hand when the time is 3:15. Example: 10 sided die, a person rolls a die. You are the house. What should you charge the person if they are rewarded with 1 x whatever they roll. It is a top propriety trading firm. The thing I can't do that well is multiply numbers in my head. I am aware that there are a lot of easy tricks to do math mentally, but I do not know them yet. I haven't been exposed to probability really since high school and I had only one statistics class well over a year and a half ago. I haven't taken a straight math class since finite math and calculus for non-majors since freshman year. They also mention that they hire from all majors such as history etc... How do they expect you to know all of this stuff? I am assumign one has to just study up on trading interviews and master the material unless they are a math major. I do think some of these questions were pretty easy in hindsite and that if I prepare I shouldn't have too many problems in the future. I believe that I got most of them right with a little directional prodding from the interviewer. I am also unsure as to how they would interview me face to face... I.E. if I am allowed to use a paper and a simple calculator and think out loud or not. The main issue here I think is not cracking under pressure. I was getting grilled really bad but I think that I kept my composure and kept trying without giving up. Needless to say, interviews like this can put you in a bad mood if you are unprepared or can't handle the pressure. At the conclusion the guy let up and was really nice. I could tell he was a good guy but was just trying to do his job and interview as best as he can.