 Solution

ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2014/iii/paper-35/2/i/solution

Codex  0 Created 2026-10-03 Updated 2026-10-06

(X, Y) = d (Y, X)

: their joint probability distribution is unchanged by swapping the coordinates. Thus for every measurable set

A

P (X \in A) = P ((X, Y) \in A \times Y) = P ((Y, X) \in A \times Y) = P (Y \in A) .

Exchangeability implies identical marginal distributions, but does not imply independence.

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