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.

Problems on Train with Explanation and Shortcuts

Formula : .

Train Speed = Distance / Time.

Points to Remember .

To change km/hr into m/sec, we need to multiply it by 5 / 18. .

Example:.

90 km/hr means.

90 x 5 / 18.

= (5 x 5 ).

= 25 m/sec.

And if we need to convert m/sec into km/hr, we multiply it by 18 / 5.

Example:.

90 m/sec means.

90 x 18 / 5.

= ( 18 x 18 ).

= 324 km/hr.

Time taken by a train of length l meters to pass a pole or standing man or a signal post is equal to the time taken by the train to cover l meters.
Time taken by a train of length l meters to pass a stationary object of length b meters is the time taken by the train to cover (l + b) meters.
Suppose two trains or two objects bodies are mo...

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Clock and Time Problems, Tips and Tricks, Formula

These are the different type of questions asked from this topic.

Type 1: Find the time when the angle between the two hands are given.

Type 2: Find the angle between the 2 hands when the time is given.

Type 3: Find the time, when clocks gaining/losing time.

Type 4: Find the time in the mirror image.

ക്ലോകിലെ ഓരോ അക്കങ്ങൾക്കിടയിലെ കോണളവ്= 30°.
മിനിറ്റ് സൂചി ഓരോ മിനുറ്റിലും 6° ചുറ്റും.
മണിക്കൂർ സൂചി ഒരു മിനുറ്റിൽ ½°ചുറ്റും.
ഒരുദിവസം Hour, Minute സൂചികൾ 22 തവണ ഒന്നിന് മീതെ ഒന്നായി വരും.
ക്ലോകിലെ സൂ...

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Combinations and Permutations

Permutation and combination related questions are common in PSC and Bank exams.

Before going to Combinations and Permutations, first lean about factorial. .

If n is a positive integer then, factorial of n is denoted as n! . .

4! = (1 x 2 x 3 x 4 ) = 24.

Permutations are for lists of items, whose order matters and combinations are for group of items where order doesn’t matter. in other words, .

When the order of items doesn\\\'t matter, it is called as Combination.
When the order of items does matter it is called as Permutation.

The number of permutations of n objects taken r at a time is determined by using this formula:.

C(n,r)=n!/((n−r)!r!) .

Combination : Picking a team of 3 people from a football coaching group of 10. C(10,3) = 10!(3!(10−3)!) = 120. ....

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Tricks and Tips for Boat and Stream type Questions