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Weighted Variant Selection

A hard SQL mock interview question on DataDriven. Practice with AI-powered feedback, real code execution, and a hire/no-hire decision.

Domain
SQL
Difficulty
hard
Seniority
L5

Interview Prompt

The A/B testing platform uses rollout percentages to weight feature flag selection. Compute each flag's selection probability (its rollout divided by the total rollout across all flags) and its cumulative probability (the running sum of probabilities in rollout order).

Summary

Select a row using cumulative weight probabilities.

How This Interview Works

  1. Read the vague prompt (just like a real interview)
  2. Ask clarifying questions to the AI interviewer
  3. Write your sql solution with real code execution
  4. Get instant feedback and a hire/no-hire decision

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