GATE Civil Engineering (CE) 2019 Shift 1 Solved Paper

A wastewater is to be disinfected with $35\mathit{m}\mathit{g}/\mathit{L}$ of chlorine to obtain $99\%$ kill of microorganisms. The number of micro-organisms remaining alive $\left({\mathit{N}}_{\mathit{t}}\right)$ at time $\mathit{t}$, is modelled by ${\mathit{N}}_{\mathit{t}}={\mathit{N}}_0{\mathit{e}}^{-\mathit{k}\mathit{t}}$, where $\mathit{N}0$ is number of microorganisms at $\mathit{t}=0$, and $\mathit{k}$ is the rate of kill. The wastewater flow rate is $36{\mathit{m}}^3∕\mathit{h}$, and $\mathit{k}=0.23$ min-If the depth and width of the chlorination tank are $1.5\mathit{m}$ and $1.0\mathit{m}$, respectively, the length of the tank (in $\mathit{m}$, round off to 2 decimal places) is _____________-