Interviewing frenzy

Optimal stopping and hiring strategy interview question

This is a classic easy-to-medium difficulty puzzle that tests your grasp of optimal stopping — a decision-making framework where you must commit to an irreversible choice under incomplete information. Quant firms and trading desks use variants of this to assess how candidates think about sequential decisions, trade-offs between information and commitment, and the structure of a dynamic problem.

The question requires you to recognize that simply accepting the best candidate you've seen so far is not optimal. Instead, the key is to identify a threshold or decision rule that balances the risk of rejecting a strong early candidate against the possibility of finding someone better later. Once you establish the optimal strategy, you can calculate the exact probability it succeeds.

• Threshold-based decision rules under uncertainty
• Trade-off between exploration and commitment
• Reasoning about conditional probabilities across sequential outcomes