Jane Street

Interview Question

Quant Trader Intern Interview
Jane Street

There are two balls in a bag, each either black or white. If you draw a white ball, put it back, then draw again and it's still a white ball, what is the probability of drawing a white ball the next time?

Unlock the Full Solution

Enter your email to get instant access to the complete solution, explanation, and similar practice problems.

Insights on 100+ quant firms, understand where to apply, and maximize your chances.

Get the official 2025 QB Quant Firm Tier List

Check your email inbox — you should get the interview in 1-2 minutes!