Boats & Streams
Boat & Stream: Quick Revision
Essential formulas and shortcuts for PreLim & Mains
1 Basic Formulas
Effective Speeds
Downstream (D) = B + S
Upstream (U) = B − S
Finding Components
Boat Speed (B) = (D + U) ÷ 2
Stream Speed (S) = (D − U) ÷ 2
2 Golden Shortcuts
⭐ Shortcut: Same Distance Logic
Speed ratio is the inverse of time ratio. (Useful for Mains)
Downstream Time : Upstream Time = 2 : 3
→ Speed Ratio = 3 : 2
→ Speed Ratio = 3 : 2
Student Hacks
- Downstream speed MUST be greater.
- Ratio Questions: Up/Down = Down Speed / Up Speed.
- Swimmer logic = Boat logic.
Avoid Mistakes
- ❌ Adding stream speed for Upstream.
- ❌ Forgetting Unit Conversion (min → hr).
- ❌ Solving Algebra when formulas work.
30-Second Revision Box
D = B + S
U = B − S
B = (D + U)/2
S = (D − U)/2
Remember this → Boat & Stream is done ✅
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241 questions in this topic. Each quiz draws 10, marked as in the Prelims, with explanations.