18 men built a ship model in 7 days. How many days would it take for 15 men?

Options

A. 8.7
B. 8.5
C. 8.4
D. `(43)/(5)`

Answer

To solve the problem of how many days it would take for 15 men to build a ship model, we can follow these steps:

### Step-by-Step Solution:

1. **Determine the Total Work Done**:
The total work done can be calculated using the formula:
\[ \text{Total Work} = \text{Number of Men} \times \text{Number of Days} \]
For 18 men working for 7 days, the total work is:
\[ \text{Total Work} = 18 \text{ men} \times 7 \text{ days} = 126 \text{ man-days} \]

2. **Set Up the Equation for 15 Men**:
Let \( x \) be the number of days it would take for 15 men to complete the same amount of work. The equation for the work done by 15 men is:
\[ \text{Total Work} = 15 \text{ men} \times x \text{ days} \]
Therefore, we have:
\[ 15x = 126 \]

3. **Solve for \( x \)**:
To find \( x \), divide both sides of the equation by 15:
\[ x = \frac{126}{15} \]

4. **Calculate \( x \)**:
Performing the division:
\[ x = 8.4 \]

### Conclusion:
It would take 15 men approximately **8.4 days** to build the ship model.