Thursday, 19 April 2012

Permutations and combinations

In every area we use Permutations and combinations which are the part of Algebra 2, but generally the permutations and combinations are use in mathematics filed. They are the fundamental principles of counting. The main difference between the permutations and combinations according to board of secondary education Andhra Pradesh is, when the orders means a lot then it is said to be permutations and if the order means nothing then it is said to be combinations. Just take examples for both: -
A permutation is also an ordered combination. Permutations are of two types: -
-Repetition is allowed.
-No repetition.
Example of Permutations: - If the 893 is the password combination of any id then it cannot be 398. Because to apply the 398 we cannot open the id, to open the id we have to insert the 8-9-3 in exact order. In this order matters alot.
Combination is also two types: -
-Repetition is allowed.
-No repetition
Example of Combination:- If I am saying that my vegetable salad is a combination of onions, tomatoes and chilies, then the order means nothing to us, we do not take care the order, either they could be in order like onions, tomatoes and chilies or chilies, tomatoes and onions. It will be same vegetarian salad. No matters what is the order.
Permutations and combinations formula,
Permutations formula for repetition: -n r.
Permutations formula without repetition: - n ! / (n –r) !,
Combination formula for repetition : - (n + r – 1) / r = (n + r – 1) ! / r ! (n – 1) !,
Permutations formula without repetition: - n ! / r ! (n – r) ! = (n / r),
By applying the above formulas we can solve the any type of permutations and combination problems.


In upcoming posts we will discuss about Measures of central tendency and Geometric proofs in Grade XII. Visit our website for information on Ogive

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