Study Material — 2 PYQs (2023–2023) · Concept Notes · Shortcuts
IBPS RRB PO Boats & Streams is a frequently tested subtopic — 2 previous year questions from 2023–2023 papers are included below with concept notes, key rules and shortcut tricks.
Imagine walking on a moving escalator. If you walk in the same direction as the escalator, you move faster. If you walk against it, you move slower. Similarly, water current helps or hinders boat movement
💡Key Rules
Speed of boat in still water = (Downstream speed + Upstream speed) ÷ 2. Speed of current = (Downstream speed - Upstream speed) ÷ 2. Downstream speed = Boat speed + Stream speed. Upstream speed = Boat speed - Stream speed.
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Formula Block
Memorise — at least one formula appears in every paper
• Downstream Speed = Speed in still water + Speed of stream
• Upstream Speed = Speed in still water - Speed of stream
• Speed in still water = (Downstream + Upstream) ÷ 2
• Speed of stream = (Downstream - Upstream) ÷ 2
• Time = Distance ÷ Speed
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Exam Patterns
What examiners ask — read before attempting PYQs
Questions typically ask for boat speed in still water, stream speed, time calculations, or distance problems. Common formats include round trips, meeting point problems, and comparative speed questions.
Apply formulas
Boat speed in still water = (10 + 4) ÷ 2 = 7 km/hr
Stream speed = (10 - 4) ÷ 2 = 3 km/hr
Worked Example 2: A man can row 6 km/hr in still water. Stream speed is 2 km/hr. How long to travel 16 km downstream and return?
Calculate times
Time downstream = 16 ÷ 8 = 2 hours
Time upstream = 16 ÷ 4 = 4 hours
Total time = 2 + 4 = 6 hours
Trick for Round Trips: Total time = Distance × 2 × Boat speed ÷ (Boat speed² - Stream speed²)
Common Mistake: Students often confuse downstream and upstream directions
💡Remember
downstream means 'with the flow' (faster), upstream means 'against the flow' (slower). Another trap is adding stream speed when calculating upstream speed instead of subtracting it. Always check if your downstream speed is greater than upstream speed.
The speed of a boat in still water is 10 km/h and the stream speed is 2 km/h. How much time will it take to travel 36 km downstream and then return to the starting point?
Practice 2easy
A boat takes 4 hours to travel 56 km downstream. If the boat's speed in still water is 12 km/h, what is the speed of the stream?
Practice 3easy
A boat travels 60 km upstream in 5 hours. If the boat's speed in still water is 14 km/h, what is the speed of the stream?
Practice 4medium
A boat's speed in still water is 20 km/h. It travels 100 km downstream and 80 km upstream, taking a total of 9 hours. What is the speed of the stream?
Practice 5medium
A boat takes 6 hours to travel 120 km downstream. If the boat's speed in still water is 18 km/h, how long will it take to travel 100 km upstream?
Practice 6medium
A man rows a boat 30 km downstream and 20 km upstream, taking 4 hours and 5 hours respectively. What is the speed of the stream?
Practice 7medium
The speed of a boat in still water is 15 km/h and the speed of the stream is 3 km/h. How much time will the boat take to travel 72 km downstream and then return to the starting point?
Practice 8medium
A boat can travel 60 km upstream in 5 hours. If the speed of the stream is 2 km/h, what is the speed of the boat in still water?
Practice 9hard
A boat travels 84 km downstream in 4 hours. The ratio of the boat's speed in still water to the stream's speed is 5:1. How much time will the boat take to travel 63 km upstream?
Practice 10hard
A boat's speed in still water is 20 km/h. The boat travels from point A to point B (downstream) in 2 hours and returns from B to A (upstream) in 3 hours. What is the speed of the stream?
Practice 11hard
A boat takes 5 hours to travel 120 km downstream and 8 hours to travel the same distance upstream. If a man rows a boat at the speed of the stream, how far will he travel in 6 hours?