A man can row with the stream at 11 km/hr and against the stream at 8 km/hr. The speed of the stream is -----

Options

A. 3 km/hr
B. 9.5 km/hr
C. 1.5 km/hr
D. 6 km/hr

Answer

To find the speed of the stream, we can use the information given about the man's rowing speeds with and against the stream.

### Step-by-Step Solution:

1. **Identify the given speeds:**
- Speed of the man with the stream (downstream) = 11 km/hr
- Speed of the man against the stream (upstream) = 8 km/hr

2. **Let the speed of the man in still water be \( M \) km/hr and the speed of the stream be \( S \) km/hr.**

3. **Set up the equations based on the given information:**
- When rowing downstream:
\[ M + S = 11 \quad \text{(1)} \]
- When rowing upstream:
\[ M - S = 8 \quad \text{(2)} \]

4. **Solve the equations simultaneously:**
- From equation (1):
\[ M = 11 - S \quad \text{(3)} \]
- Substitute equation (3) into equation (2):
\[ (11 - S) - S = 8 \]
- Simplify the equation:
\[ 11 - 2S = 8 \]
- Rearranging gives:
\[ 2S = 11 - 8 \]
\[ 2S = 3 \]
\[ S = \frac{3}{2} = 1.5 \text{ km/hr} \]

5. **Conclusion:**
- The speed of the stream is \( 1.5 \) km/hr.

### Final Answer:
The speed of the stream is **1.5 km/hr**.

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