# Boat & Stream: Concept, Questions, Formula, Tricks

By BYJU'S Exam Prep

Updated on: September 25th, 2023

Boat and Stream Questions is one of the frequently asked topics in the SSC and Railway exam. Before learning the concepts of the exam one must be aware of the terms that are used in the questions. We can easily solve the boat and stream questions by understanding the stream’s adaptive and countercurrent flow.

We have included boat and stream questions for SSC CGL/CHSL/CPO/Steno etc. in this post that can raise your performance level and help you fetch good marks. In addition to that, we have shared short tricks and formulas for boat and stream concepts that will be very beneficial to you. You can also find boat and stream questions pdf from the direct link shared in this article.

Table of content

## Boat and Stream Concept

A boat or person is said to be moving at a pace that is in the stream’s flow if they are moving in the stream’s direction, i.e., in the same direction as the stream. On the other hand, a boat or person is said to be moving at a counterclockwise pace if they are travelling against the flow of the stream.

The only way to answer boat and stream questions for SSC exams is to comprehend the formulae, such as speed of boat = like the speed of boat = (speed in the direction of the stream + speed in the direction of the flow) / 2 or speed of the stream = (speed in the direction of the stream – of the stream Opposite move) / 2.

## Boat and Stream Formula

In the case of Upstream:

When the boat moves against the current of the river (i.e. in opposite direction), then the relative speed of the boat is the difference in the speed of the boat and the stream. It is known as upstream speed.

Remember it with UP as going up the hill means against the direction of the force (speed) of the river.

If the speed of boat or swimmer is x km/h and the speed of the stream is y km/h then,

• Speed of boat upstream = (x − y) km/h

In the case of Downstream:

When the boat moves with the current of the river (i.e. in the same direction), then the relative speed of the boat is the sum of the speed of the boat and stream. It is known as downstream speed.

Remember it with DOWN as going down the hill means towards the direction of the force (speed) of the river.

If the speed of the boat or swimmer is x km/h and the speed of the stream is y km/h then,

• Speed of boat downstream = (x + y) km/h

Important Points

• When the speed of the boat is given then it means speed in the still water, unless it is stated otherwise.

Some Basic Formulas

• Speed of boat in still water is
= ½ (Downstream Speed + Upstream Speed)
• Speed of stream is
= ½ (Downstream Speed – Upstream Speed)

## Boat and Stream Questions Tricks

The following tips may help you finish the boat and stream questions for SSC exams from the quantitative aptitude section more quickly and accurately:

• The first and most crucial piece of advice is that a candidate has to memorise the key formulae in order to appropriately respond to boat and stream questions for SSC CGL. Knowing the boat and stream formula by heart will enable applicants to correctly respond to simple boat and stream questions.
• Keep in mind that the phrases upstream and downstream may not be used precisely in the question; instead, in the direction of flow or against the direction of flow may be used.
• Candidates should not rush through reading the guidelines provided in the instructions since doing so will assist them to avoid making careless mistakes in the questions.
• As the boat and stream questions for SSC exams are often straightforward and not overly difficult, make sure you do not become anxious when reading the length of the question or the phrases used in the questions. Just the way the question is written makes it sound difficult.
• Additionally, it must be understood that the more frequently a person applies the boat and stream formula to the questions, the more probable it is that he or she will be able to provide accurate answers.
• Only diligent study will enable a candidate to ace the boat & stream questions from the concept.

## Types of Boat and Stream Questions for SSC CGL

Type 1: When the distance covered by the boat in downstream is the same as the distance covered by the boat upstream. The speed of the boat in still water is x and the speed of the stream is y then the ratio of time taken in going upstream and downstream is,

Short Trick:

Time taken in upstream : Time taken in Downstream = (x+y)/(x-y)

Example:

A man can row 9km/h in still water. It takes him twice as long as to row up as to row down. Find the rate of the stream of the river.

Solution:

Time taken in upstream: Time taken in Downstream = 2:1

Downstream speed : Upstream speed = 2:1

Let the speed of man = B, & speed of stream = S

B + S : B – S = 2/1

By using Componendo & Dividendo

B/R = 3/1, R = B/3

R = 9/3 = 3km/h

Type 2: A boat covers a certain distance downstream in t1 hours and returns the same distance upstream in t2 hours. If the speed of the stream is y km/h, then the speed of the boat in still water is:

Short Trick: Speed of Boat = y [(t2 + t1) / (t2 – t1)]

Example

A man can row a certain distance downstream in 2 hours and returns the same distance upstream in 6 hours. If the speed of the stream is 1.5 km/h, then the speed of man in still water is

Solution:

By using the above formulae

= 1.5 [(6+2) / (6-2)] = 1.5 * (8/4) = 1.5 * 2 = 3km/h

Type 3: A boat’s speed in still water at x km/h. In a stream flowing at y km/h, if it takes it t hours to row to a place and come back, then the distance between two places is

Short Trick: Distance = [t*(x2 – y2)]/2x

Example

A motorboat can move at a speed of 7 km/h. If the river is flowing at 3 km/h, it takes him 14 hours for a round trip. Find the distance between two places.

Solution: By using the above formulae

= [14 * (72 – 32)]/2* 7 = [14 * (49-9)]/2*7

= 14*40/2*7 = 40km

Type 4:  A boat’s speed in still water at x km/h. In a stream flowing at y km/h, if it takes t hours more in upstream than to go downstream for the same distance, then the distance is

Short Trick: Distance = [t*(x2 – y2)]/2y

Example

A professional swimmer challenged himself to cross a small river and back. His speed in the swimming pool is 3km/h. He calculated the speed of the river that day was 1km/h. If it took him 15 mins more to cover the distance upstream than downstream, then find the width of the river.

Solution: By using the above formulae

Distance = [t*(x2 – y2)]/2y

= [(15/60) (32 – 12)]/2*1

= [(1/4) * 8] / 2

= 2/2 = 1 km.

Type 5: A boat’s speed in still water at x km/h. In a stream flowing at y km/h, if it covers the same distance up and down the stream, then its average speed is

Short Trick: Average speed = upstream * downstream / man’s speed in still water

Note: The average speed is independent of the distance between the places.

Example

Find the average speed of a boat in a round trip between two places 18 km apart. If the speed of the boat in still water is 9km/h and the speed of the river is 3km/h?

Solution: Average speed = upstream * downstream / man’s speed in still water

Average speed = 6 * 12 / 9 = 8km/h

## Boat and Stream Questions PDF

We have compiled the “Important Boats and Streams Question PDF for SSC and Railway Exams”. These questions have been asked in previous years’ papers too. Candidates who are willing to appear in any of the SSC and Railway exams can download Boat and Stream Questions PDF so that they get all the important questions in one place. And it will become very easy for aspirants to practice and revise before the exam.

Hence, you are aware of all the tips and tricks to solve boat and stream questions, you must gear up and start preparing for the exam. You can also take the SSC Mock test, especially designed by subject-matter experts, to enhance your preparation level.

 Related Articles: SSC & Railway Exams SSC CGL Previous year Papers SSC CGL Job Profile SSC CGL Books

All The Best !!!

DREAM, STRIVE & SUCCEED With US!

Check Out