Question

Tutorial : Permutation and Combination (Silent Points)
Part 2

Answer 1

1. 'n' different things can be arranged among themselves in 'n!' ways.


2. Identical things Can be arranged among themselves in only one way.

3. Permutation of 'n' different things taken 'r' at a time equal to :


4. Permutation of 'n' things in which 'p' things are alike of one kind, 'q' things are alike the second king, 'r' things are alike of the third kind and rest are \[{ different=\quad \frac { n! }{ p!q!r! } }\]

5. ‘r’ objects can be selected out of 'n' different ways or objects in

Answer 2

6. ‘r’ things can be selected out of ‘n’ identical things in only one way.
7. if \[\huge ^nP_r \] denotes the number of permutation of ‘n’ different things, taking ‘r’ at a time, then
\[^{ n }P_{ r }=n(n-1)(n-2).......(n-r+1)=\frac { n! }{ (n-r)! } \]
Note that \[^{ n }P_{ n } = n! \]
8.If [\ ^nC_r\] denotes the number of combination of ‘n’ different things, taking ‘r’ @ a time then
^{ n }C_{ r }=\frac { n! }{ r!(n-r)! } =\frac { ^{ n }P_{ r } }{ r! } \quad where\quad r\le \quad n;\quad n\quad in\quad N\quad \& r\quad in\quad W

Answer 3

1-5 in Previous one!

Answer 4

http://openstudy.com/study#/updates/5007b71ce4b020a2b3bd2945

Answer 5

Permutation = nPr = n! / (n-r)!
Combination = nCr = nPr / r!

Answer 6

sorry Rohan... did you write this
http://www.tekoclasses.com/ENGLISH%20PDF%20PACKAGE/9%20PERMUTATION%20&%20COMBINATION%20PART%202%20of%204.pdf