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Balance of Arms

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
L4

Interview Prompt

An experimentation platform needs to confirm each test's groups are balanced before readout. For each experiment, find the unique users in the control group, the unique users in treatment, and the treatment-to-control ratio.

Summary

Every test has two sides. Count who actually landed on each.

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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