A rectangular tank having a base 80 m by 50 m and depth 7 m is filled with water. In how much time can the water be emptied by a pipe of which the cross-section is a square of side 25 cm. if the water runs through the pipe at the rate of 20 km per hour?
1
22.6 hours
2
22.4 hours
3
21.6 hours
4
21.4 hours