Solution (source code)

= Solution

The positive result's <posterior odds> of true to false are
$$
\frac{\mathbb P(T\mid P)}{\mathbb P(F\mid P)}=R\frac{1-\beta}{\alpha}.
$$
Thus being more likely true requires $\boxed{R>\alpha/(1-\beta)}$. The question's weak inequality is necessary; equality gives a tie rather than a strict preference.