How to Solve Boats and Stream Maths Quickly

Extending from the basic knowledge rules of boats and stream math problems, here we have given some examples on how to solve boat and stream math problems quickly and easily using quick tricks and basic methods too. The aim is to give you knowledge of basic rules and math shortcut tricks to prepare you for all kind of competitive exams.

• What time will be taken by a boat to cover a distance of 128 km along the stream, if speed of boat in still water is 24 km/h and speed of stream is 8 km/h?

Answer: Here we have

B = 24 and S = 8.

So, D = 24 + 8 = 32

Since the boat is moving along the stream, it means the boat is moving downstream.

Therefore, 128/32 = 4 is the required time.

• A boat goes 48 km downstream in 20 hour. It takes 4 hour more to cover the same distance against the stream. What is the speed of the boat in still water?

Answer: From the question we have

Downstream speed of the boat = 48/20 = 2.4

And Upstream speed of the boat is 48/24 = 2.

Therefore, the speed of the boat in still water = (2 + 2.4) / 2 = 2.2 km/h.

• Ashutosh can row 24 km/h in still water. It takes him twice as long to row up as to row down the river. Find the rate of Stream.

Answer: Let’s consider that, Ashotosh takes 1 unit of time to row downstream and 2 units of time to row upstream.

Here we see that Boat’s speed is 3/2. But in question we have been given that the boat’s speed is 24 km/h.

Therefore we can write 24 * 1/3/2 = 24 * 2/3 = 16 unit.

So from the figure we can write

Downstream speed = 16 * 2 = 32 km/h.

Again,

 D = B + S

32 = 24 + S

S = 8 km/h.

• A motor boat can travel at 10 km/h in still water. It travelled 91 km downstream in a river and then returned to the same place, taking altogether 20 hour. The rate of flow of river is how much?

Answer: We know that upstream speed is

U = boat’s speed (B) – speed of the current (S)

And downstream speed is

D = boat’s speed (B) + speed of the current (S)

Therefore,

Placing B = 10, i.e. motorboat’s speed, we get

10² – S² = 91

S (rate of river flow) = 3 km/h.

Read More

Boats and Streams Tricks for Bank Exams

Boats and Stream math is one of the important topic in bank exam questions as well as in SSC exams. Timing plays an important role in competitive exams both bank exams and SSC exams. Boats and Stream math questions are one of the easiest problems that we usually miss in Competitive exams. 

Here i will provide you all type of shortcut tricks on boats and stream questions come in competitive exams like bank exams. Not just stopped at shortcut tricks on boats and stream, here you will be provided with all basic math formulas on boats and stream and also basic concepts. 

To the readers of this blog, please go through all the boat and stream formulas, basic concepts and short tricks on boat and stream problems. Based on banking exams questions some difficult problems with solutions for bank exams have also been given here.

Important things to keep in mind:

Basic Concepts:

Downstream: Downstream (D) is calculated by adding up the boat's speed running in the same direction with that of the current.

∴ D = Boat's Speed (B) + Speed of the Current (S)

Upstream: Upstream (U) is calculated by subtracting the speed of the current from the speed of the Boat running in the opposite direction of the current.

∴ U = Boat's Speed (B) - Speed of the Current (S)

Boat's speed in still water: (Downstream + Upstream)/2

Speed of Stream: (Downstream - Upstream)/2

Quick Formulas: Click here

The formulas are always important for faster calculations and find out answers quickly. But here, using basic concepts problems or questions on boats and stream are being tried to solve without remembering formulas. 

Example:

• Rajesh can row 12 km/h in still water. It takes him twice as long to row up as to row down the river. Find the rate of stream?

Answer: Let's consider Rajesh as a boat (B) who's speed is 12 km/h.

We know that there is an inverse relation between time and speed, which is 

Time ∝ 1/Speed

So, let's consider that to go downstream Rajesh takes 1 unit of time and to go upstream he takes 2 unit of times, since Rajesh takes twice as long to row up as to row down the river.

We know that speed of Boat in still water = (D+U)/2

From above we get Downstream speed is 2 and upstream speed is 1.

So, (2 + 1)/2 = 3/2

But it is given that boat's speed or Rajesh's speed in still water is 12 km/h.

∴ we can write 12 * 1/3/2 = 12 * 2/3 = 8.

So the downstream speed is 8 * 2 = 16

                                                                                                        

We know that 

Downstream = Boat's speed + Speed of Current

∴ 16 = 12 + Speed of Current

Speed of Current = 4 km/h.

For more examples visit: Examples with Solutions

Read More