Tricks and Tips for Boat and Stream type Questions

Shortcut tricks on boats and streams are one of the most important topics in exams. These are the formulas and examples on Boats and Streams (Cyclist and the wind or Swimmer and stream) questions. These examples will help you to better understand shortcut tricks on boats and streams questions.

There are multiple types of questions asked from these topics.

The speed of the boat in still water and the speed of stream will give in questions, You have to find the time taken by boat to go upstream and downstream.
The speed of the boat in up and down stream will give in question, you need to find the average speed of the boat.
The speed of boat to go up or down the stream will give in question, you need to find speed of boat in still water and speed of stream
The time taken by boat to reach a place in up and downstream will given in question, you need to find the distance to the place

Basic Formulas

In water, the direction along with stream is called Downstream.
The direction of the boat against the stream is called Upstream.
The speed of boat or man in calm water which we denoted by sb.
The speed of water or stream that denoted by sw.
Speed of boat in downstream (along the river) = (sb + sw)
Speed of boat in upstream (against the river) = (sb - sw)
Speed of boat in still water ss = ½(sb + sw)
Speed of water current (Rate of stream) sc = ½(sb – sw)

Sample Questions

A man can row 18km/hr in still water. the speed of the man in downstream is thrice the speed in upstream. Find the rate of the stream?.

Let assume, Speed of man in upstream = x

Speed of man in downstream = 3x

Speed of man in still water ss = ½( x + 3x)

= 2x

We know speed of man in still water = 18

ie, x = 9

Rate of stream = ½(27 – 9) =9 km/hr.

Time and Work Problems - Shortcut Tricks and Formulas

Problems Type 1: .

A can finish work in X days. .

B can finish work in Y days.

Both can finish in Z days = (X*Y) / (X+Y). .

Problems Type 2: .

Both A and B together can do work in T days.

A can do this work in X days.

then, B can do it in Y days = (X*T) / (X-T) .

Problems Type 3: .

A can finish work in X days.

B can finish work in Y days.

C can finish work in Z days.

Together they can do work in T days = (X*Y*Z)/ [(X*Y)+(Y*Z)+(X*Z)] .

Problems Type 4: .

A can finish work in X days.

B can finish work in Y days.

A*X = B*Y.

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ഗണിത സൂത്രവാക്യം

ആദ്യത്തെ \'n\' എണ്ണൽ സംഖ്യകളുടെ തുക = n(n+1) /2.
ആദ്യത്തെ \'n\' ഒറ്റ സംഖ്യകളുടെ തുക = n².
ആദ്യത്തെ \'n\' ഇരട്ട സംഖ്യകളുടെ തുക = n(n+1).
ആദ്യത്തെ \'n\' എണ്ണൽ സംഖ്യകളുടെ വർഗ്ഗങ്ങളുടെ തുക = n(n+1)(2n+1) / 6.
ആദ്യത്തെ \'n\' എണ്ണൽ സംഖ്യകളുടെ ക്യൂബുകളുടെ തുക = [n(n+1)/ 2]².
ആദ്യ പദം \'a\', പൊതു വ്യത്യാസം \'d\' ആയാൽ n-മത്തെ പദം കാണാൻ = a+ (n -1) d.
ആദ്യ പദം \'a\', പൊതു വ്യത്യാസം \'d\' ആയാൽ, n പദങ്ങളുടെ തുക കാണാൻ = n/2[2a + (n - 1)d].
ആദ്യ പദവും (t1), n...

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Faster Percentage Calculation

The quickest way to calculate percentages is to multiply numbers first and handle two decimal places later.

For example, 20% of 70 is 20 x 70 = 1400, so the answer is 14. .

70% of 20 is also 14.

To calculate the percentage of 72 or 29, then round up and down to the nearest multiple (70 and 30 respectively) to get a quick approx result.

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Tricks and Tips for Boat and Stream type Questions