A 2 L bioreactor is being operated as a chemostat, at a flow rate of 0.8 L/h and sterile feed of 10 g/L substrate. The bacterial growth follows Monod kinetics at a maximum specific growth rate of 0.6 h\(^{-1}\) with a Monod constant of 0.5 g/L and a biomass yield coefficient of 0.4 g/g. The exit biomass concentration is _________ g/L. (Round off to one decimal place)