Water is pouring into a cuboidal reservoir at the rate of 60 litres per minute. If the volume of reservoir is $108 m^3$ , find the number of hours it will take to fill the reservoir.

Volume of the reservoir$= 108 m^3 = 108000 L [\because 1 m^3 = 1000 L]$

Volume of water flowing into the reservoir in 1 minute = 60 L

Time taken to fill the reservoir$=\frac{Volume of reservoir}{Rate of flow of water}=\frac{108000}{60}=1800 minutes$

Time taken = $\frac{1800}{60}hours=30 hours$

It will take 30 hours  to fill the reservoir.