CBSE · Class 6-12

Class 11 · Mathematics (041)

Unit 6 · Class 11Mathematics (041)

Algebra

Permutations and Combinations

Fundamental counting principle, permutations, combinations, and their applications.

Lessons

4 concepts

1
Fundamental Principle of Counting
If a task has $m$ ways and a second (independent) task has $n$ ways, both together have $m \times n$ ways.
2
Permutations
$^nP_r = \dfrac{n!}{(n-r)!}$ . Arrangements of $n$ distinct objects taken $r$ at a time.
3
Combinations
$^nC_r = \dfrac{n!}{r!(n-r)!}$ . Selection (order doesn't matter).
4
Applications
Committee formation, arrangement of letters, seating around a round table $(n-1)!$ .

Skills to practise

Skill · medium

Permutations and Combinations — Practice (coming soon)

Practice bank for this unit is in progress. You can still read the lessons above.