An exact product of three rational probabilities

Proved

WorkbookSource.problem_5422

by wamlart · Sep 12, 2026 · Mathlib 0df444a (Lean v4.33.1)

lean-workbooksource-checked

Case RGG: $\frac 12 \cdot \frac 12 \cdot \frac 14 = \frac 1{16}$ .

Source: InternLM Lean-Workbook, record lean_workbook_5422 (Apache-2.0). The complete source proposition and explicit variable declarations are preserved.

Preamble

import Mathlib
open Real Nat

Formal statement

theorem WorkbookSource.problem_5422 : (1 / 2 : ℚ) * (1 / 2) * (1 / 4) = (1 / 16)  :=  by sorry

Source

https://huggingface.co/datasets/internlm/Lean-Workbook/blob/main/lean_workbook.json, record lean_workbook_5422; Apache-2.0

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