Hi friends, we are discussing the topic Permutations and combinations of ssc board Andhra Pradesh in this blog. The combinations and permutations are part of algebra which is part of Discrete math. In combination the order of things is not important, example: the fruit salad is combination of papaya, mango, grapes, apple we do not care what order of fruits is in.
The combination is two types: 1) repetition 2) not repetition.
Allowed the Repetition: in your pocket the number of coins can be repeated (2, 2, 2, 5, 5, 10, 10)
Repetition is not allowed: in the lottery numbers repetition is not allowed (5, 67, 45, 96, 24, 54)
Example of the combination: when we are choosing balls the possibilities of selection can be 1, 2, 3 balls.
Order does matter: 123, 132, 231, 321, 312, 213. The formula of combination is aCb
a! (! this symbol is used for the factorial operation)
aCb =---------
b!(a-b)!
Here, a is the number of things from which we have to choose b number of things.
The formula is applied on example where we have to choose 3 out of 5 different balls:
5! 5! 120
----------- = --------- = 10 ways of combination.
3!(5-3)! 3!*2! 12
Permutation is an order of combination in which the order does not change (visit for more information on permutation). The lock is the best example of permutation; the permutation is totally different to the combination. Permutations are basically of two types:
Here a*a*a*.........(b times)=ab
a! (!- this symbol is used for the factorial operation)
aPb=-------
(a-b)!
An Example of this permutation can be when we have to pick 2 out of 5 balls in all possible ways:
5! 5*4*3*2*1 120
---- – = ---------- ---- = 20 ways
(5-2)! 3*2*1 6
In upcoming posts we will discuss about Math Blog on Grade XI and Properties of quadrilaterals. Visit our website for information on How to Calculate Standard Deviation
The combination is two types: 1) repetition 2) not repetition.
Allowed the Repetition: in your pocket the number of coins can be repeated (2, 2, 2, 5, 5, 10, 10)
Repetition is not allowed: in the lottery numbers repetition is not allowed (5, 67, 45, 96, 24, 54)
Example of the combination: when we are choosing balls the possibilities of selection can be 1, 2, 3 balls.
Order does matter: 123, 132, 231, 321, 312, 213. The formula of combination is aCb
a! (! this symbol is used for the factorial operation)
aCb =---------
b!(a-b)!
Here, a is the number of things from which we have to choose b number of things.
The formula is applied on example where we have to choose 3 out of 5 different balls:
5! 5! 120
----------- = --------- = 10 ways of combination.
3!(5-3)! 3!*2! 12
Permutation is an order of combination in which the order does not change (visit for more information on permutation). The lock is the best example of permutation; the permutation is totally different to the combination. Permutations are basically of two types:
1. Repetition is compulsory: the code of the lock is: 555. The repetition is allowed in this case and order does not matter.
Simple formula for repetition: abHere a*a*a*.........(b times)=ab
2. No repetition allowed: In this we have to reduce number of available choices for each time
Example: in the pool game number of balls is fixed. One ball is used one time and no repetition is allowed for using the same ball. The formula of no repetition permutation:a! (!- this symbol is used for the factorial operation)
aPb=-------
(a-b)!
An Example of this permutation can be when we have to pick 2 out of 5 balls in all possible ways:
5! 5*4*3*2*1 120
---- – = ---------- ---- = 20 ways
(5-2)! 3*2*1 6
In upcoming posts we will discuss about Math Blog on Grade XI and Properties of quadrilaterals. Visit our website for information on How to Calculate Standard Deviation
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