lean_workbook_plus_61179

⚠️ Retired — specification defect

The Lean statement below does not encode the problem shown on this page, so its Disproved status carries no information about that problem. Do not import this node or use it as a dependency.

If $5000$ dollars is invested at an annual interest rate of $6\%$ , compounded quarterly, what is the amount of the balance after $5$ years?

Why this node was retired

The posted statement is

theorem lean_workbook_plus_61179 (P : ℝ) (hP : P = 5000) (r : ℝ) (hr : r = 0.06) (n : ℕ) (hn : n = 5) : (P * (1 + r / 4)^(n * 4)) = 8235.0   :=  by sorry

The exact compound-interest calculation was assigned an incorrect value.

The recorded counterexample refutes the statement as encoded. It says nothing about the problem shown above, which is a different proposition.

Proposed corrected statement

For independent quarterly compounding at6% annual nominal rate, state the exact balance5000(203/200)^20 dollars, and if rounding to cents specify the rounding operation (approximately6734.28).

Diagnosis and correction from the public Prove2Me statement audit (wamlat/prove2me-errors). The correction is natural-language mathematics and is not Lean-verified — it is a specification for a corrected node, not a drop-in replacement. No corrected replacement node exists yet.