In a double pipe cocurrent heat exchanger, operating at steady state, oil (specific heat capacity = 2100 J kg⁻¹ °C⁻¹) entering at 7 kg s⁻¹ at 100 °C is used to heat water (specific heat capacity = 4200 J kg⁻¹ °C⁻¹) flowing at 3.5 kg s⁻¹ from 20 °C to 50 °C. If the overall heat transfer coefficient is 291 W m⁻² °C⁻¹, the required heat transfer area (in m²) is _____ (rounded off to one decimal place).