We know that water in canal forms a cuboidThe dimensions are Breadth =30dm=3mHeight =12dm=1.2mWe know thatLength = distance covered bt water in 3 minutes = velocity of water in m/hr× times in hoursBy substituting the values=20000×6030​So we getLength =10000mWe know thatVolume of water flown in 30 minutes =1×b×hBy substituting the valuesVolume of water flows in 30 minutes =10000×3×1.2=36000 m3Consider A m3 as the are irrigatedSo we getA×1009​=36000On further calculationA=400000 m2Therefore, the area to be irrigated is 400000 m2.