// QUANT PREPARATION · STUDY METHODS
Outcry Arcade vs Brainstellar: Puzzle Practice
Brainstellar’s public puzzle library groups problems by difficulty and topic. A useful follow-up to reading a puzzle is deriving a general expression and testing a changed version. Outcry’s puzzle practice can be used alongside that written reasoning.
Worked example: geometric probability
Five points are independently uniform on a circle. What is the probability they all fit inside some semicircle?
Ignore coincident and exactly antipodal points, which have probability zero. If a containing semicircle exists, one point uniquely anchors its clockwise boundary with all other points in the next half-circle.
For a particular anchor the chance is (1/2)^4. The five anchor events are disjoint except for zero-probability boundaries, so the total is 5/16. For n ≥ 2, the same argument gives n/2^(n−1).
A practice sequence
- Explain why the anchor events can be added without double-counting.
- Check n = 2 and n = 3 before generalising.
- Draw a counterexample to an incorrect independence assumption.
Compare progress using fresh work
After working the geometric probability 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 geometric probability
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 Brainstellar and Outcry?
Use a study resource to learn or review a method, then solve a changed example and explain your reasoning. The geometric probability 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.