An effective rainfall of $2$-hour duration produced of flood hydrograph peak of $200 \: m^3/s$. The flood hydrograph has a base flow of $20 \: m^3/s$. If the spatial average rainfall in the watershed for the duration of storm is $2$ cm and the average loss rate is $0.4$ cm/hour, the peak of $2$-hour unit hydrograph (in $m^3/s-cm$ up to one decimal place) is ________
