A batch cultivation of E. coli follows zeroth order Monod’s growth kinetics. The cell growth is terminated when the residual dissolved oxygen concentration attains 10% of its saturation value and oxygen mass transfer coefficient ( ) L k a reaches its maximum value ( ) 1 80h − . The saturation value of dissolved oxygen concentration is 3 0.007 kg m− . If the maximum specific growth rate and yield coefficient ( ) X O2 Y are 1 0.2 h − and 1 2 1.5 ( )( ) kg cells kg O − , respectively, then the final cell concentration in 3 kg m− (rounded off to two decimal places) at the end of the batch cultivation is _