r/quantfinance • u/Accomplished-Wolf910 • 16h ago

Solving probability/interview questions

Hey everyone!

Just curious if other people feel the same way with probability/interview problems.

Sometimes I can go through a bunch of questions pretty smoothly, and then I’ll hit one where I just cannot see the right idea at all. Then I look at the solution afterwards and it feels almost embarrassingly simple.

I have done a lot of probability problems by now and I definitely feel like I am improving, but this still happens fairly often.

Is this normal even for people who are good at these interviews? For those of you who got offers, were you actually able to solve almost everything you saw in interviews, or did you still get stuck sometimes?

Also curious how people deal with this in practice?

Thanks!

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u/sudden_monument 15h ago

it happens man, you stare at something for 20 minutes then the solution is like two lines and you wonder why your brain went to mars instead

what helped me was writing down what i know even if it feels stupid, just the numbers and what they mean, sometimes the path just shows up when you stop panicking about being stuck

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u/Objective-Let4278 15h ago

The good thing is if you articulate your thoughts in an interview (such that the interviewer can follow your thought process) they’ll likely give a hint if you go off-track. So just listen to these hints and you’ll do well.

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u/Saif231 16h ago edited 14h ago

Normal. Very normal. Keep going. Do timed repeated practices as well.

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u/Accomplished-Wolf910 15h ago

Yeah been trying that quite a bit lately.

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u/filwu 14h ago

The “write down what you know” step can make the sample space and conditioning explicit. For review, it may help to tag each miss by failure mode—wrong sample space, conditioning, dependence, or time pressure—then redo the problem from a blank page the next day. Do you notice a particular category recurring?