Recent questions and answers in Permutations and Combinations

The no of triangle whose verticles on decagon but none of whose side came f

answered Dec 31, 2019 by kumaraditya95042

1 answer

Ballot Theorum

answered Mar 24, 2015 by vijayalakshmi.r

1 answer

In how many ways can a mixed doubles game in tennis can be arranged from 5 couples, if no husband and wife play in the same game?

answered Nov 23, 2013 by rvidyagovindarajan_1

1 answer

$S=\{1,2,3..............12\}$ $A,B,C $ are disjoint equivalent subsets of $S$ so that $A\cup B\cup C=S$. How many such sets $A,B,C$ can be formed?

answered Sep 14, 2013 by rvidyagovindarajan_1

1 answer

There are 9 Judges in a beauty contest. A particular candidate is selected as the winner if she gets maximum number of votes in favour. In how many ways a particular candidate is declared the winner?

answered Sep 6, 2013 by rvidyagovindarajan_1

1 answer

For $n\geq 4$, $1!+2!+3!+4!+.....n!$ is always

answered Sep 6, 2013 by rvidyagovindarajan_1

1 answer

There are 10 men. 5 of them are to be selected for a team. In how many ways this can be done if a particular person is to be selected in the team and if A is selected then B also is to be selected?

answered Sep 6, 2013 by rvidyagovindarajan_1

1 answer

If $^nC_3=220$, then $n=?$

answered Sep 6, 2013 by rvidyagovindarajan_1

1 answer

If $^{a^2-a}C_2=^{a^2-a}C_4,$ then $a=?$

answered Sep 6, 2013 by rvidyagovindarajan_1

1 answer

$^nC_r+2.^nC_{r-1}+^nC_{r-2}=?$

answered Sep 6, 2013 by rvidyagovindarajan_1

1 answer

If $ ^{n-1}C_6+^{n-1}C_7>^nC_6$, then $n$ is ?

answered Sep 6, 2013 by rvidyagovindarajan_1

1 answer

If $^nP_r=720^nC_r$, then r=?

answered Sep 6, 2013 by rvidyagovindarajan_1

1 answer

If $^nC_{r-1}=36$, $^nC_r=84$ and $^nC_{r+1}=126$, then $r$ = ?

answered Sep 6, 2013 by rvidyagovindarajan_1

1 answer

If $^nC_{12}=^nC_8,$ then $n = ?$

answered Sep 6, 2013 by rvidyagovindarajan_1

1 answer

In how many ways a mixed double games can be arranged from 8 married couples if no husband and wife play in the same game?

answered Sep 5, 2013 by rvidyagovindarajan_1

1 answer

$(100)!+1$ is divisible by?

answered Sep 5, 2013 by rvidyagovindarajan_1

1 answer

A bag contains 3 black 4 white and 2 red balls, all balls being different. The number of selection of at the most 6 balls so that each selection has balls of all the 3 colours is ?

answered Sep 5, 2013 by rvidyagovindarajan_1

1 answer

How many different pair of letters ( , ) can be made from the letters if the word 'STATICS'?

answered Sep 5, 2013 by rvidyagovindarajan_1

1 answer

There are $20$ boxes numbered $1,2,......20$. Five boxes are selected at random and are arranged in ascending order. In how many ways this can be done so that no. $10$ is present in each selection and it comes in $3rd$ place in the arrangement.?

answered Sep 5, 2013 by rvidyagovindarajan_1

1 answer

There are 7 identical black balls and 4 identical white balls. In how many ways can they be arranged in a row so that no two white balls are adjacent?

answered Sep 5, 2013 by rvidyagovindarajan_1

1 answer

20 identical marbles of green colour and 20 identical marbles of white colour can be arranged in a row in how many ways so that no two same colour marbles are adjacent?

answered Sep 5, 2013 by rvidyagovindarajan_1

1 answer

There are $10$ white and $10$ black balls each set numbered 1,2,3......10. The no. of ways in which they can be arranged so that no two adjacent balls are of same colour is ?

answered Sep 5, 2013 by rvidyagovindarajan_1

1 answer

The no. of ways in which 20 different pearls of two colours can be set alternatively on a necklace, there being 10 pearls of each colour, is ?

answered Sep 5, 2013 by rvidyagovindarajan_1

1 answer

16 different things are to be distributed among 3 persons A,B,C so that B gets 1 more than A and C get 2 more than B. In how many ways this can be done?

answered Sep 4, 2013 by rvidyagovindarajan_1

1 answer

Four couples (husband and wife)decide to form a committee of four members. How many committees can be formed so that no couple finds a place in it?

answered Sep 4, 2013 by rvidyagovindarajan_1

1 answer

The no. of ways in which any four letters can be selected from the word 'ENTREE' is

answered Sep 4, 2013 by rvidyagovindarajan_1

1 answer

The total no. of words that can be formed using the alphabets $a,b,c,d,e,f$ taking 3 at a time so that each word has atleast one vowel is ?

answered Sep 4, 2013 by rvidyagovindarajan_1

1 answer

The no. of ways in which 8 different flowers can be strung to form a garland so that 4 particular flowers are not separated is?

answered Sep 4, 2013 by rvidyagovindarajan_1

1 answer

How many 6 digit numbers can be formed using the digits 1,2,3,4 so that each of the digits should come atleast once in each number?

answered Sep 4, 2013 by rvidyagovindarajan_1

1 answer