Compute odds under time pressure
OptiverQuantitative Trader · Online Assessment
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This question evaluates probabilistic reasoning and combinatorial calculation skills, including conditional probability, distributional thinking and the ability to convert probabilities into odds.
Answer a timed probability question: An urn contains r red, b blue, and g green balls (r,b,g ≥ 0, r+b+g ≥ 3). You draw 3 balls without replacement. Compute the probability that you draw at least two reds within 90 seconds, and present a fast mental-math method that scales to general parameters. Extend your solution to (i) drawing with replacement, (ii) conditional probability given that the first ball was green, and (iii) odds ratio form suitable for quick estimation.
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