To find the cost of plastering the walls and bottom of the open tank, we need to follow these steps:
### Step 1: Calculate the Surface Area to be Plastered
The open tank has the following dimensions:
- Length (L) = 25 m
- Width (W) = 12 m
- Depth (H) = 6 m
The surface area to be plastered includes:
1. The bottom of the tank
2. The four walls of the tank
#### Bottom Area:
The area of the bottom of the tank is given by:
\[ \text{Area}_{\text{bottom}} = L \times W = 25 \, \text{m} \times 12 \, \text{m} = 300 \, \text{m}^2 \]
#### Wall Areas:
The tank has two pairs of opposite walls:
- Two walls of dimensions (Length x Height)
- Two walls of dimensions (Width x Height)
The area of the two longer walls:
\[ \text{Area}_{\text{long walls}} = 2 \times (L \times H) = 2 \times (25 \, \text{m} \times 6 \, \text{m}) = 2 \times 150 \, \text{m}^2 = 300 \, \text{m}^2 \]
The area of the two shorter walls:
\[ \text{Area}_{\text{short walls}} = 2 \times (W \times H) = 2 \times (12 \, \text{m} \times 6 \, \text{m}) = 2 \times 72 \, \text{m}^2 = 144 \, \text{m}^2 \]
#### Total Wall Area:
Now, we can find the total wall area:
\[ \text{Total Wall Area} = \text{Area}_{\text{long walls}} + \text{Area}_{\text{short walls}} = 300 \, \text{m}^2 + 144 \, \text{m}^2 = 444 \, \text{m}^2 \]
#### Total Surface Area:
Now, we add the bottom area to the total wall area:
\[ \text{Total Surface Area} = \text{Area}_{\text{bottom}} + \text{Total Wall Area} = 300 \, \text{m}^2 + 444 \, \text{m}^2 = 744 \, \text{m}^2 \]
### Step 2: Calculate the Cost of Plastering
The cost of plastering is given as Rs 15 per square meter. Therefore, the total cost can be calculated as:
\[ \text{Total Cost} = \text{Total Surface Area} \times \text{Cost per m}^2 \]
\[ \text{Total Cost} = 744 \, \text{m}^2 \times 15 \, \text{Rs/m}^2 = 11160 \, \text{Rs} \]
### Final Answer:
The cost of plastering the walls and bottom from the inside is **Rs 11,160**.
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