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Optiver·Software Engineer·Online Assessment (OA)·Junior

Junior
May 2026

Summary

Optiver OA had a format I hadn't seen before: probability ranking under a tight time constraint. No coding, just raw statistical intuition from a small dataset. Weird, fast, and honestly kind of fun once I understood what they were after.

Questions Asked (1)

Q1

You are given a table of historical data (e.g., five months of test scores for three students) and three events. Rank the events by probability from highest to lowest. You have 90 seconds.

Product Analytics & MetricsA/B Testing & Experimentation
Author's notes

The time limit is the real trick here.

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AI HintsAI Generated

Suggested Approach

First, quickly scan the data to identify the trend and variability for each student. Then, for each event, assess how likely it is based on the observed pattern, using simple probability estimates. Finally, rank the events from most to least likely, explaining your reasoning briefly.

Pro tip: Focus on the relative likelihoods rather than exact probabilities; interviewers care more about your thought process and ability to reason under time pressure than getting the 'right' answer.

1. Understand the Data

Quickly examine the table: note the time period, the students, and the range of scores. Identify any obvious trends (e.g., improving, declining, stable) and variability.

2. Interpret Each Event

Read each event carefully and determine what it implies about the data. For example, 'Student A scores above 90' or 'Student B's score decreases'.

3. Estimate Probabilities

For each event, use the historical data to estimate its likelihood. Consider the frequency of similar occurrences, trends, and variability. Use simple heuristics like 'more likely than not' or 'unlikely'.

4. Rank and Justify

Order the events from highest to lowest probability. Briefly explain your ranking, referencing specific data points or patterns.

Key Points to Mention

  • Trend analysis: identify if scores are increasing, decreasing, or stable over time.
  • Variability: consider the spread of scores to assess consistency.
  • Base rates: use the frequency of past occurrences to inform probability.
  • Conditional probability: if events are related, consider dependencies.
  • Time constraints: prioritize quick, reasonable estimates over precise calculations.
  • Communication: clearly state your assumptions and reasoning.

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.