The Dimensions of the Cistern are 10 m x 8m x 6m :

A pipe with square cross-section is supplying water to a cistern which was initially empty. The area of cross-section is 4 cm² and the nozzle velocity of water is 40 m/s. The dimensions of the cistern are 10 m x 8m x 6m. Then the cistern will be full in

1. 9.5 hours
2. 9 hours
3. 8 hours 20 minutes
4. 8 hours