// QUANT PREPARATION · STUDY METHODS
Outcry Arcade vs Brilliant: Probability Practice
Brilliant’s public site describes interactive maths and coding learning. Outcry’s probability practice applies related ideas to generated quantitative exercises. Learn the concept first, then test whether you can build the likelihoods and denominator without a worked example beside you.
Worked example: Bayesian updating
A drawer contains three fair coins, two coins with P(H) = 3/4 and one double-headed coin. Pick a coin uniformly and observe two heads. What is the probability it is double-headed?
Use unnormalised group weights: 3 × (1/2)² = 3/4, 2 × (3/4)² = 9/8, and 1 × 1² = 1. The common 1/6 selection factor cancels.
Multiply by 8 to get weights 6, 9 and 8. The double-headed posterior is 8/(6 + 9 + 8) = 8/23 ≈ 34.78%. Repeated evidence updates the likelihood of each type; it does not make the three types equally likely.
A practice sequence
- Keep prior counts distinct from likelihoods.
- Compute the total evidence probability before normalising.
- Try HT instead of HH and explain which hypothesis becomes impossible.
Compare progress using fresh work
After working the Bayesian updating example, change one condition and explain why your method still applies or needs to change. A correct answer is more useful when you can identify the model, justify the calculation and state its limits.
Outcry’s exercises supply their own game rules. Its mocks show counts, clocks, navigation and marking, with a source check identifying published employer details and practice adaptations. Check your invitation for the process you will actually sit.
Practise Bayesian updating
Use the worked method, then attempt the linked exercise. Check access requirements and the exercise’s stated rules before starting.
Frequently asked questions
How should I combine Brilliant and Outcry?
Use a study resource to learn or review a method, then solve a changed example and explain your reasoning. The Bayesian updating exercise above gives a concrete starting point; no single resource or practice score guarantees a hiring outcome.
Are the example and timings an employer’s actual test?
No. This is original educational material with explicitly stated assumptions. Outcry mock settings are practice choices unless its source check identifies a published format element.
Where can I check pricing and access?
Use each provider’s current official pages. Outcry’s Pricing page lists its current plans and included features; this guide does not assert a universal competitor price or that every exercise is free.
Related
Outcry is not affiliated with the named resource or any recruiting firm. These are educational comparisons of study approaches, not an exhaustive feature audit or a claim of better hiring outcomes. Sources and examples reviewed 26 October 2026.