The capacity of a water tank is 36 kl, when it is full. Now, it is half. If `1/3` of water is taken out, then how much water will be given to the tank to fill up completely?

Options

A. 24
B. 21
C. 18
D. 15

Answer

To solve the problem step by step, let's break it down:

1. **Determine the full capacity of the water tank**:
The capacity of the tank when full is given as 36 kL.

2. **Calculate the current amount of water in the tank**:
The tank is currently half full. Therefore, the amount of water in the tank is:
\[ \text{Current Water} = \frac{36 \text{ kL}}{2} = 18 \text{ kL} \]

3. **Calculate the amount of water taken out**:
It is stated that \( \frac{1}{3} \) of the current water is taken out. To find this amount:
\[ \text{Water Taken Out} = \frac{1}{3} \times 18 \text{ kL} = 6 \text{ kL} \]

4. **Determine the remaining amount of water in the tank**:
After taking out the water, the remaining amount of water in the tank is:
\[ \text{Remaining Water} = 18 \text{ kL} - 6 \text{ kL} = 12 \text{ kL} \]

5. **Calculate the amount of water needed to fill the tank completely**:
To find out how much water is needed to fill the tank to its full capacity, we subtract the remaining water from the full capacity:
\[ \text{Water Needed} = 36 \text{ kL} - 12 \text{ kL} = 24 \text{ kL} \]

Thus, the amount of water that needs to be added to fill the tank completely is **24 kL**.