The volume of a tank is 72 cubic metres. Water is poured into it at the rate of 60 litres per minute. How much time will it take to fill the tank?

20 hours

1${m }^{3 }$ = 1000 litres,

⇒ Therefore, total volume of the tank =  72${m }^{3 }$ = 72000 litres,

⇒ Total time taken to fill the tank = $\frac{72000}{60}$ = 1200 minutes,  ..($\frac{Total volume}{Rate of water poured in minute}$ = Total Time taken)

⇒ $\frac{1200}{60}$ = 20 hours,