A village, having a population of 4000, requires 150 litres water per head per day. It has a tank which is 20 m long, 15 m broad and 6 m high. For how many days will the water of this tank last?

#### Solution

\[\text { A village has population of 4000 and every person needs 150 L of water a day }. \]

\[\text { So, the total requirement of water in a day }= 4000 \times 150 L = 600000 L\]

\[\text { Also, it is given that the length of the water tank is 20 m} . \]

\[\text { Breadth = 15 m }\]

\[\text { Height = 6 m }\]

\[\text { Volume of the tank = length }\times \text { breadth } \times \text { height }= 20 \times 15 \times 6 = 1800 m^3 \]

\[\text { Now, 1 }m^3 = 1000 L \]

\[i . e . , 1800 m^3 = 1800 \times 1000 L = 1800000 L\]

\[\text { The tank has 1800000 L of water in it and the whole village need 600000 L per day }. \]

\[ \therefore \text { The water in the tank will last for } \frac{1800000}{600000}\text { days, i . e . , 3 days } .\]