Which distributions should I know for quant interviews?

Binomial, geometric, Poisson, uniform, exponential, and normal - their means, variances, and when each arises. Knowing how they relate (for example, Poisson as a limit of the binomial) is frequently tested.

What techniques speed up random-variable problems?

Linearity of expectation (which ignores dependence), indicator variables, and symmetry arguments. These turn many summation-heavy problems into one-line answers.

How important is variance versus expectation in interviews?

Both matter. Trading roles care about variance and risk as much as the mean, so expect questions that ask you to reason about spread, not just the expected value.

Random Variables Interview Questions

Working fluently with distributions, expectation, and variance separates strong candidates. These questions cover discrete and continuous random variables and their key properties.

This area covers discrete and continuous distributions, expectation and variance, moments, and key results like the properties of the normal and exponential - the building blocks behind everything from dice games to pricing models.

Interviews reward people who reach for linearity of expectation, symmetry, and indicator variables instead of brute-force summation. Practising these shortcuts is what makes hard-looking problems quick.

140 random variables questions · 102 free to practise now.

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Frequently asked questions

Which distributions should I know for quant interviews?: Binomial, geometric, Poisson, uniform, exponential, and normal - their means, variances, and when each arises. Knowing how they relate (for example, Poisson as a limit of the binomial) is frequently tested.
What techniques speed up random-variable problems?: Linearity of expectation (which ignores dependence), indicator variables, and symmetry arguments. These turn many summation-heavy problems into one-line answers.
How important is variance versus expectation in interviews?: Both matter. Trading roles care about variance and risk as much as the mean, so expect questions that ask you to reason about spread, not just the expected value.