A first-order homogeneous liquid-phase reaction (A→B) occurs in a non-ideal isothermal reactor operating at steady state. The variance (σ²) of residence time distribution (RTD) from a pulse tracer experiment is 4 min². The volumetric flow rate of the feed is 5 L min⁻¹ and volume of the reactor is 25 L. The reaction rate constant is 0.4 min⁻¹. Based on the tanks-in-series model, the conversion (in %) is _______ (rounded off to one decimal place).