A tank 10 m long and 4 m wide is filled with water . How many litres of water must be drawn off to make the surface sink by 1m. (1000 L= 1 cubic metre )

Options

A. 20 kilolitre
B. 40 kilolitre
C. 50 kilolitre
D. none of these

Answer

To find out how many litres of water must be drawn off to make the surface of the tank sink by 1 meter, we will follow these steps:

### Step 1: Calculate the volume of water to be removed
The volume of water that needs to be removed can be calculated using the formula for the volume of a rectangular prism:

\[ \text{Volume} = \text{Length} \times \text{Width} \times \text{Height} \]

Given:
- Length of the tank = 10 m
- Width of the tank = 4 m
- Height to sink = 1 m

Substituting the values into the formula:

\[ \text{Volume} = 10 \, \text{m} \times 4 \, \text{m} \times 1 \, \text{m} = 40 \, \text{m}^3 \]

### Step 2: Convert cubic meters to litres
We know that 1 cubic meter is equal to 1000 litres. Therefore, to convert the volume from cubic meters to litres, we multiply by 1000:

\[ \text{Volume in litres} = 40 \, \text{m}^3 \times 1000 \, \text{litres/m}^3 = 40000 \, \text{litres} \]

### Step 3: Convert litres to kilolitres
Since 1 kilolitre is equal to 1000 litres, we can convert the volume in litres to kilolitres:

\[ \text{Volume in kilolitres} = \frac{40000 \, \text{litres}}{1000} = 40 \, \text{kilolitres} \]

### Final Answer
Therefore, the amount of water that must be drawn off to make the surface sink by 1 meter is **40 kilolitres**.

---