Given , radius of tank, r1=40 cm.
Let height of water level in tank in half an hour = h1
Also, given internal radius of cylindrical pipe r2=1 cm
And speed of water = 80 cm/s. i.e in 1sec water flow = 80 cm.
∴ in 30 ( min) water flow =80×60×30=144000 cm
According to the question.
Volume of water in cylindrical tank = Volume of water flow from the circular pipe In half an hour
Hence, the level of water in cylindrical tank rise 90 cm in half an hour.