FA-84412 / Betting odds conversion / Member archive

Bookmaker margin reported as the overround · case 02

The margin column repeats the overround (4.71 instead of 4.50 for 1.91/1.91).

Member previewVariant 2 · 3 implementations · 7 checks per implementation

Case contract

Market book analysis for decimal prices (strings, each > 1, else "invalid"). Implied probability is 1/d; book = sum of implied probabilities. Return [overround percent (book - 1) * 100, bookmaker margin percent (1 - 1/book) * 100, fair prices d * book for proportional margin removal], every number rounded half up to two decimals (negative values are rounded toward +infinity at the half) and formatted with two decimals.

Why this case matters

Trading tools report overround and margin separately and derive no-vig fair prices.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
control standard juice	`["4.71", "4.71", ["2.00", "2.00"]]`	`["4.71", "4.50", ["2.00", "2.00"]]`	Failed

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