$3.$ A watershed is divided into four subareas as shown. Runoff from each subarea will contribute to flow at gaging station G$.$ Rain falls as shown in the rainfall hyetograph $($intensity vs$.$ time$)$ in the table shown below. Derive the bar hydrograph at gage G assuming no losses.

Tim $($hr$)123$

Rainfall intensity $($mm$/$hr$)0\mathrm{.}250\mathrm{.}60\mathrm{.}4$