An ideal plug flow reactor $($PFR$)$ is used to remove COD from wastewater. The influent

COD concentration is $C_0=100m\frac{g}{L}.$ If the reaction is first order with a rate constant

of $k=2\mathrm{.}0h{r}^{-1}$ What detention time $(T)$ in hours is required to achieve an effluent

COD concentration of $C=5m\frac{g}{L}?$ Round your answer to $1$ digit past the decimal $($e$.$g$.,$

$x.x$ and do NOT enter units.