Radius of pipe = 7/2 cm
Rate of water flow = 36 km/h
= 36 × 5/18 m/s
= 10 m/s
= 10 × 100 cm/s
= 1000 cm/s
∴ Volume of water flowing in 1 second = πr^{2}h
= π.7/2.7/2.1000 cm^{3}
= π.7.7.250 cm^{3} …..(1)
Radius of tank (R) = 35 cm
Height of tank (H) = 1 m = 100 cm
∴ Volume of tank = πr^{2}H
= π.35.35.100 cm^{3} …(2)
∴ Time taken to fill the tank = Volume of tank/Volume of water flowing in 1 second
= π × 35 × 35 × 100/π × 7 × 7 × 250 seconds
= 10 seconds