SSC Exam Quantitative Aptitude Study Material: A conceptual guide for Permutation

Jun 21, 2016 17:17 IST

SSC is well known for the recruitment of Group ‘B’ and ‘C’ posts under the Ministries/Departments in The Government of India. SSC organizes various examinations like Combined Graduate Level examination, Combine Higher Secondary Level, Stenographer and for SI/DP/CAPF, etc., throughout the year having almost the same Exam Pattern. The Exam paper is comprised of basically 4 subjects.

a. General Intelligence & Reasoning

b. English language & Comprehension

c. Quantitative Aptitude

d. General knowledge

For more detail, click the link given below.

SSC SI, CAPF & ASI Exam 2015: Exam Pattern

SSC Combined Higher Secondary Level (10+2) Exam 2014: Exam Pattern

SSC JHT & Hindi Pradhyapak and Sr. / Jr. Translators Exam 2014: Exam Scheme & Syllabus

SSC Stenographer 2016: Take a look of Exam Pattern, Syllabus and Selection Procedure

So, Jagranjosh.com has introduced a brief plan for revising topics at the time of examination. In this article, Permutation which sometimes appears more difficult to understand in terms of  making possible arrangements.

Permutation

The arrangement of a number of things taking some or all of them at a time is called permutation. If there are ‘n’ number of things and we have to select ‘r’ things at a time then the total number of permutation is denoted by

For example if there are 3 candidates A ,B and C for the post of president and vice president of a college , since we have to select only 2 candidates , it can be done in 3! Ways. i.e. (A, B) (B, C) (A, C) (B, A) (C, B) and (C, A). Here order of arrangement matters.

Restricted Permutation:

Sometimes we have to find out the number of permutation keeping few specific objects at specific places. In this case, we find out the number of permutation of filling remaining vacant places by the remaining objects.

If r objects are taken out of n dissimilar objects

Repetition of things:

The number of permutation formed by taking r things at a time out of n things in any object arrangement such that each object can be taken any number of time is nr.

Circular permutation:

If we fix one of the objects around the circumference of a circle then number of permutation of n different thing taken all at a time is (n-1)! Ways. It will be same as by putting (n-1) objects at (n-1) places.

Illustration: - In how many different ways can the letters of the word 'THERAPY' be arranged so that the vowels never come together?

(1) 720

(2) 1440

(3) 5040

(4) 3600

(5) 4800

Solution:  Total number of letters is 7, and these letters can be arranged in 7! ways        .

= 1 x 2 x 3 x 4 x 5 x 6 x 7 = 5040 ways

There are seven letters in the word THERAPY including 2 vowels. (E, A) and five consonants.

Consider two vowels as one letter.

We have 6 letters which can be arranged in 6P6

= 6 ways.

But vowels can be arranged in 2! ways.

Hence, the number of ways, all vowels will come

together = 6! x 2!

= 1 x 2 x 3 x 4 x 5 x 6 x 2 = 1440

Total number of ways in which vowels will never

come together = 5040 - 1440 = 3600

Ans: (4)

So, Jagranjosh.com has introduced a brief plan for revising topics at the time of examination. In this article, Permutation which sometimes appears more difficult to understand in terms of  making possible arrangements.

Permutation

The arrangement of a number of things taking some or all of them at a time is called permutation. If there are ‘n’ number of things and we have to select ‘r’ things at a time then the total number of permutation is denoted by

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