When the speed of a boat in still water is 4 km/h and the rate of stream is 2 km/h, find downstream speed of the boat?

Options

A. 6 km/h
B. 5 km/h
C. 2 km/h
D. 7 km/h

Answer

To find the downstream speed of the boat, we can use the formula:

**Downstream Speed = Speed of Boat in Still Water + Speed of Stream**

### Step-by-Step Solution:

1. **Identify the speed of the boat in still water**:
- The speed of the boat in still water is given as 4 km/h.

2. **Identify the speed of the stream**:
- The rate of the stream is given as 2 km/h.

3. **Apply the formula for downstream speed**:
- Downstream speed is calculated by adding the speed of the boat in still water to the speed of the stream.
- So, we have:
\[ \text{Downstream Speed} = \text{Speed of Boat in Still Water} + \text{Speed of Stream} \]
\[ \text{Downstream Speed} = 4 \text{ km/h} + 2 \text{ km/h} \]

4. **Calculate the downstream speed**:
- Adding the two speeds together:
\[ \text{Downstream Speed} = 6 \text{ km/h} \]

5. **Conclusion**:
- Therefore, the downstream speed of the boat is **6 km/h**.

### Final Answer:
The downstream speed of the boat is **6 km/h**.

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