Question:
A boat travels 24 km upstream in 6 hours and 30 km downstream in 5 hours. What is the speed of the boat in still water?
A boat travels 24 km upstream in 6 hours and 30 km downstream in 5 hours. What is the speed of the boat in still water?
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In boat-stream problems, $b = \frac{\text{downstream speed} + \text{upstream speed}}{2}$.
Updated On: Aug 1, 2025
6 km/h
5 km/h
- 7 km/h
- 8 km/h
\bigskip
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The Correct Option is B
Solution and Explanation
- Step 1: Find upstream speed - \[ \text{Upstream speed} = \frac{\text{Distance}}{\text{Time}} = \frac{24}{6} = 4 \ \text{km/h} \]
- Step 2: Find downstream speed - \[ \text{Downstream speed} = \frac{30}{5} = 6 \ \text{km/h} \]
- Step 3: Let boat speed in still water = $b$ and stream speed = $s$ - Then: \[ b - s = 4 \] \[ b + s = 6 \]
- Step 4: Solve the system - Adding: $2b = 10 \implies b = 5$.
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