Boats & Streams: The Only 2 Formulas You Need to Know

Boats & Streams questions carry 1-2 marks. With just 2 formulas, you can solve any question in this topic.

The 2 Core Formulas

Formula 1: Speed of boat in still water = (Downstream speed + Upstream speed) / 2. Formula 2: Speed of stream = (Downstream speed - Upstream speed) / 2. That's it. Every boats and streams question uses these two formulas.

Key Concepts

Downstream: Boat and stream move in same direction → speeds add. Upstream: Boat moves against stream → speeds subtract. Speed = Distance/Time applies throughout.

Common Question Types

Type 1: Given downstream and upstream speeds, find boat speed and stream speed. Type 2: Given boat speed and stream speed, find time for a journey. Type 3: Round trip — go downstream and return upstream. Total time = D/DS + D/US where D = one-way distance.