Handshake Problem

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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Profit and loss is the one of major question section in Competitive exams. These formulas will be helpful for your upcoming Exams like PSC, SSC, IBPS and Other Competitive Exams. .


Cost Price(CP) : The Price at which a particular item purchased, is called its Cost Price.
Selling Price (SP): The price at which a particular item is sold, called its Selling Price.
Profit: If Selling Price of an item is more than Cost Price , then vendor is said to have a Profit.
Loss: if Selling Price of an item is less than Cost Price, the vendor said to have a Loss.


Formulas Profit = SP – CP.
Profit % = Profit/(CP)×100.
SP = ((100+Profit% )/100)×CP.
CP = (100/(100+Profit%))×SP.


Loss = CP – SP.
Loss% = Loss/(CP)×100.
SP = ((100-loss%)/100)×CP.
CP = (100/(100-loss%))×SP.


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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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